The text to flag a question as too broad is currently:
There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.
Like my previous meta question, this also seems to be unfitting with the goals of Puzzling.
Should this be changed, can it be changed, and if so, what to?
For example:
There are either too many possible solutions, or good solutions would be too long for this format. Please add details to narrow the solution set so that the puzzle can be solved and explained in (some size of text).