Dispell psionic = dispell magic, magic resistance = psionic resistance, etc. and vice versa
Yeah, it smacked me in the forehead that it was an obscure term for something pretty obvious ("how do they interact?"), right before I reloaded the page and saw your response.
In this survey I called out Crown of Madness as the prime example of Wizards nerfing Enchantment (and offensive Illusion) spells too hard. They used to be too powerful in 3e and now the majority of them are absolutely terrible.
If charm person is any guide, you're right. I like Ultimate Psionics' take on charms way better than 5e's, so far.
Ultimate Psionics is an impressive tome for sure, but the amount of rules and powers and flexibility is just immense. There are a myriad of balance issues in it, though nothing that screams out "broken" right away (and nothing that can't be adjusted). 5e doesn't need that much oomph though. It needs just a nice basic Psionic class with a power list and perhaps some items/monsters about the theme too.
UP seems like it would be pretty easy to adjust, as you say (ower points would be the first place I'd look). Also, the wide variety of PP costs for powers, that aren't all that tied to level, suggests that they put a lot of thought into those costs (not that this means they're any better balanced than you say).
If you have a document or link that goes into the subject of UP's balance in an illuminating way, I'd love to see it.
As for the # of powers, yeah, I guess they're a bit much for what most people want. There are roughly as many powers in UP as there are in 5e, so for my purposes, it's perfect. I have pulled back from the idea of converting over the whole powers list, though (thanks to timely intervention by the ENWorld commentariat). Instead I'm going to go through the 5e spells list, yank the stuff I don't want, flag the stuff that's so-so for review, bring in stuff I like from UP, use UP to modify 5e spells that need it, etc.