I don't know how helpful this will be, but I'll describe my experience with the puzzle in question, which I've spent a modest amount of time attacking. This doesn't answer the "what should I do?" question, at least not directly (though I do address that at the very end), but it may give some insight into why the question has remained unanswered despite hints and bounties, and maybe that will make it more apparent whether it's worth trying to provide any further help, whether posting a solution is likely to be well received, etc.

The short version is that there are two obvious thing to try to attack, I haven't successfully made progress on either, and the hints (which for some reason focus on just one of the two) don't actually help; it seems like they might confirm an answer if I had one but wasn't sure it was right, but I'm not finding them useful to guide my progress. It's as if I'm lost in a forest, I know I need to escape the forest and find a cathedral, and all the hints are telling me about the shape of the buttresses and the colour of the stained-glass windows in the cathedral: all very useful once I'm out of the forest, but not much help for getting out of it in the first place. And various things about the puzzle suggest that it may not be very precisely constructed, which reduces my motivation to look hard for a solution.

So, first there's the nonogram. It's obvious that it is a nonogram and not very difficult to solve, so I solved it. (So did someone else, who unlike me decided to post that as a partial answer.) Obviously the rhyme in the second letter is meant to help extract some sort of secret message from the nonogram solution. Most of the rhyme seems not to be actually helpful (though, who knows?, I may be missing things). The parts that seem like they mean something useful: "Ignore the bright ones, look at the dark"; maybe "the constellations you see"; "look for the stars that do not fiy ... these ones will not go very high ... running up ... count them".

The nonogram has an obvious "2021" in it, but it's not clear what to do with that. Maybe it's just for fun. The rhyme suggests looking at the bottom border (maybe other parts of the border too?) and trying to interpret the dark squares there as communicating something. ASCII in binary? Morse? Something like that. Morse is a nice idea because we have longer and shorter runs of squares, and "spark" has some nice associations with how electric telegraphs used to work. Maybe involving counting lengths of upward vertical strings of black squares from the bottom, given the last three lines of the second note. Or there's a 1-square border around the "2021" at left, right and bottom; maybe I need to use all of those. But the things I tried didn't lead anywhere promising. (E.g., suppose we look at upward-running strings of shaded squares from the bottom. We get lengths 122 12 13, or 112 11 13 if we erase the "2021" squares first. Maybe these are Morse .-- .- .- or ..- .. .-? Those make WAA, UIA, neither of which is any use. Or I could remove the 2021, getting a fairly sparse grid of dark squares, and read them upward ... as Morse again? That starts off RID which looks promising but ends up being RIDIUIIWD or RIDIUIIRD depending on exactly what the 1 looks like, both of which are pretty ridiuiiwdculous. Or maybe we're meant to do something else with the counts: 131 11 211 11 113 11 11 122 311? Nothing springs to mind. Other things I tried were similarly unenlightening. The rhyme has the same number of lines as the number of nonempty columns here, and its lines' first letters are all from {BITY} even though there are 9 of them, but again these observations haven't lead me anywhere productive.)

OK, so what now? The third note is a Reilly-ish riddle, but almost everything in it is very vague. The sort of thing I can used "backwards but not forwards": that is, if I think of a verb, I can probably work out whether there's a sense in which it's "used with u", but I don't fancy my prospects of thinking of verbs that are "used with u". The most promising line of attack is "used to specify a period of time". I've spent some minutes thinking about the Reilly, but without making any progress.

So, what about the hints? Hint 1 doesn't tell us anything that wasn't already obvious. Hint 2 might be useful for confirmation if I'd already got a guess at the answer, but it's zero help in looking for it. Hint 3 might help with the Reilly-ish riddle but there's not much to get a grip on there. (Also, "next-to-next" doesn't make any sense, though a later hint clarified the meaning, which I would certainly never have guessed without the hint.) Hint 4 might be useful, except that I'm stuck on both the second letter and the third letter. I suppose knowing that they lead to the same answer indicates that I might want to get quite a lot of letters out of the nonogram somehow? Hint 5 is another one that probably only helps as confirmation once we've already figured everything out. The "Big Hint" doesn't make much sense to me; if the Reilly doesn't "deal with words" then I've no idea what it does deal with or what these prefixes and suffixes are, and we're explicitly "looking for a word". (And I'm immediately not so sure that hint 4 is any use, since I no longer think I understand what sort of thing I'm supposed to do with the Reilly.) Maybe this just means that I'm looking for a word to describe a person who "does not deal with words"?! "Big Hint 2" just points me back to an earlier hint. (Maybe there's some clue in the exact wording of this one, I guess?) The final remark "you might have to think a bit creative in this case" makes my heart sink a bit. I mean, for solving this sort of puzzle one always has to think a bit creatively, but what that remark says to me is "My riddling might be a bit sloppy, inexact or vague", and solving riddles that are sloppy, inexact or vague is a pretty painful experience for me. ... So, the hints (aside from the first one which tells me something that was already obvious and maybe the fifth which I have no idea how to interpret) all seem to be about the Reilly, and none of them really helps me.

At this point there are two subpuzzles to attack:

• Interpreting the nonogram. Here I have what seems like a reasonable idea of what sort of thing to do, but the specific things I've tried haven't worked and I'm not sure what else to do. OP has given many many hints but none of them seems to be aimed at helping here.

• The Reilly. Most of it seems rather hard to get a grip on. The author's writing makes me suspect that English may not be their native language, which in turn makes me worry that a wordplay-based riddle may not be very precisely constructed. (Sorry!) The remark about being "creative" increases my worry on this score, as do other indications of imprecision in the puzzle. Of course it's absolutely fine for a riddle to be deliberately obscure, but any suggestion that it might be inaccurate greatly reduces my expectation that solving it will be a pleasant experience. ... And there's the "Big Hint" saying that "the third letter does not deal with words", which despite OP's claim that it's "big enough to proceed" leaves me feeling less able to make progress; if it doesn't deal with words, whatever does it deal with and how am I supposed to interpret things like "prefix" and "suffix"? And what sense can I make of the author's explanation of "next-to-next", which is all in terms of words and parts of words?

So there are two things to attack, but for both of them I'm not very hopeful that trying to attack them will actually lead anywhere useful. There are lots of hints, but they all seem to be written so as to provide no help until after the thing they're hinting at is solved. And there's the niggling concern that some of the difficulty might result from sloppiness in the puzzle construction somehow.

Let's return to the original question here, which I summarize as follows. "I posted a puzzle, but despite hints and bounties it hasn't been solved. The hints are definitely sufficient, so the problem must be that my puzzle hasn't received enough attention. How do I fix that?" I think you should at least consider the possibility that the hints are not sufficient; I've tried to solve the puzzle and even with all the hints I was not able to, and I have some reason to think I'm not unusually incompetent.

It doesn't seem as if there's no further scope for hints; e.g., for the Reilly it seems likely that there are other things that could be said about prefixes, suffixes, etc., that might help solvers, and for the nonogram-extraction you haven't really offered any hint at all beyond hint 1 saying that the rhyme uses the nonogram (which was already obvious) and hint 4 saying that the nonogram-extraction and the Reilly lead to the same answer.

So my suggestion would be to keep offering hints despite your feeling that the ones you've already given should be sufficient. If for whatever reason you can't bear to do that, maybe just post your own solution. It's possible that just giving the puzzle more visibility by repeated bounties or something will get it solved, but I would expect not; I think that for good or ill it's just harder than you think it is for solvers to guess what you have in mind.

(If you do decide to post your own solution rather than posting further hints or just waiting, then I at least will read it with interest, and I hereby promise to comment with, at minimum, some indication of whether the posted solution makes me think "Of course! I should have thought of that" or "How on earth was anyone meant to guess that that was intended?" or "wait, surely that's wrong" or what, and if possible with some comments on how (if at all) I think the puzzle could have been improved. And if you post further hints, I promise to look at the puzzle again and see if they help me solve it.)