There is a lot of confusion/complication around night owl vs early morning goals, and the current system is definitely a compromise that doesn’t work in every situation.
I recently learned about the Japanese 30-hour system, whereby times after midnight but still logically belonging to the previous day are assigned numeric times greater than 24. For example, a subway line which runs from 5am until 2am the next morning might have its hours listed as 0500-2600. Could it be helpful to specify Beeminder goal deadlines in such a fashion? It might be a neat and tidy way to distinguish between early morning and night owl deadlines that didn’t involve an arbitrary cutoff (although I realize there might still be other, internal/backend reasons for needing such a cutoff).