Zizoo, there are plenty of mismatched (i.e. Greek + Latin elements) words that have been established in contemporary English (e.g. hypersensitive), so hypoflexive has lots of company, however scruffy such company might seem to etymology mavens like me (and, I presume, Qroqqa). If you want to be consistent (though some hold that consistency is the hobgoblin of little minds, of course), you could use the Latin prefix sub-, which would give you (I think) sufflexive. Or you could search out the Greek root for "bend" (Qroqqa could help, I bet).
Zizoo, you don't really have to delete a word only because it has mixed etymology, or a fake one. 99% of Urban Dictionary users doesn't even try to justify their entries, and yours are much nicer, I.M.H.O. qroqqa was just correcting your comment, because there's something incorrect! By the way, welcome to Wordie :)