I have suggested this one before that we rename “true retention” to “retention rate”. In the current context, the word true doesn’t make any sense. And it might also suggest that there’s some sort of “untrue retention” out there.
For some perspective, the add-on that started it all used the word true to mean “retention rate excluding learn state cards”. And as the “again rate” in stats included learn cards it made sense to claim that “true retention” is somehow truer than the “again rate”.