Wow, I picked an interesting time to come back after not having played for 4 years. So a big set of restrictions JUST got made for Psionics, eh?
I agree with the idea to add additional costs to Psi via reserves (as you could effectively blast a group of enemies into oblivion at no cost whatsoever, no equipment durability damage, no expended ammunition, no consumables, etc). It's only a mild inconvenience but it does add some upkeep to Psionicists that they lacked before.
The Innervation definitely seems more tenuous to me. Like others have noted, this makes more niche psi abilities likely to practically never see use.
One possible idea that came to me: instead of making it so you simply CAN'T use non-innervated psi abilities, just give them an additional psi point cost. That way, you'll primarily stick to your innervated abilities as they're more cost-effective, but you won't be totally locked out of using more niche abilities.
Maybe you could pick entire Psi Schools to innervate instead of specific Psi Abilities.
Just a few thoughts off the top of my head.