Apart from translation matters; I'm realizing as I continue to gem grind for a few minutes once or twice a day (party lv1500 now <.<;;) that, stat scaling... really, really does favor the low-library-cost characters. If I put the same equipment on Rumia as I have on Miko and dump all her levels in mag instead of an hp/mag split, they have the same magic. They both have a permanent 16% boost and Miko currently has the highest MAG in the party (granted, Maribel is a trivial amount behind her). About 2.8m Magic.
This is with Miko wearing a +720%, +600%, and +400% MAG equipment with a Tokugawa Statue, so Maintennance is in full effect. Nitori meanwhile still has more than 50% more ATK than anyone has in MAG at 4.5m. TBH, this is more a show that even with Maintennance, Miko's costly levels/library actually makes her Normal. (granted, with double regalia boost, ho boy!)
Then I did the same with Akyuu and she had 3.1m magic, more than either- only slightly less after their permanent 16% boosts. Along with the highest def/mnd in the party (miko would beat her with more jewels), the most speed even though Renko/Miko have a lot of spd increase on equips and Akyuu has none and her base speed is horrible, etc. In further endgame territory in the future, where you have a ton more library but mostly the same gear, she'll only move further ahead.
Considering equipment becomes rather homogenous in endgame (literally everyone wants a quartz charm, practically everyone wants a regalia over the ~10% mag increase a tupsimati gives) I'm starting to think that in endgame, Akyuu actually serves really well as a hybrid tank/nuker with
for it's support+nuke hybrid benefits. The two downsides are A.Losing Placebo Effect, and B.She does have to shift a lot of levels out of HP for that. However, she still has Mega Resurrection, so she can honestly pretty well afford to do that. Hmm.
Pretty much the only thing stopping all support characters from being hybrids is that people spending ~75% of their time on support moves still probably want 80% of their levelups in HP, and at this point in the game a full set of level bonuses still roughly doubles a stat value. Your equipment loadout... isn't much different either way. Characters well-suited for hybridizing like Iku with her super strong counters and half-supportive Rumia do perfect with stuff like a half/half-ish level bonus split.
edit:I actually did the Rumia test wrong. Rumia has 3.3m magic if I give her the same stuff as Miko. Well damn. Then the 16% All By Myself... for 3.8m. That's actually starting to near Nitori's levels. XDD So, uh, yeah, cheap library is... -really- good for stats endgame. Rumia's gotten a little more EXP than Akyuu and has a little more base magic, is all.