Ahh, but the emoji indicates that it is not intended as a serious statement.
But being serious for a moment, there is no panel or individual who judges if a language is worth adding to Geany, it depends on someone with merge permission either wanting the filetype themselves, or volunteering their own time to merge a PR submitted by someone else, which they do not benefit from.
It would make it easier to get someone to merge a PR for a new filetype that they don't use if some users of the filetype try the PR and contribute that it is safe and useful (within whatever its limits are). And the PR is kept up to date if other merges cause clashes.
That reduces or even removes the need for testing by a person who does not use the filetype, has no code in that language to test with, and does not know if it is actually doing the correct thing anyway. If it is judged that enough testing is happening by people who know the filetype it means all that is needed is a merge and that is more likely to happen as it uses much less of the volunteer's time.
Dart seems to have been unfortunate that even though the PR is a data file only, so no code needs compilation, no Dart users tried it and commented that it was useful (until you now) before other changes caused clashes which were not fixed.