MoonSong
Rules-lawyering drama queen but not a munchkin
Let me first make the argument for why these aren't needed. Casters in a point-buy game almost never consider anything other than a stat gain until 12th level unless they are human. And by 12th level, casters are, IME, already on the overpowered side. So not needed.
And... combat caster is really quite good. Spell sniper can be good, though mostly for Warlocks. Lucky is great for everyone.
All that said, I think there is a niche missing, the +1 stat caster feat so that those with a +2 bonus (and thus potentially a 17 stat in point buy) get some millage out of it.
Maybe you should drop the +1, you could make the forced rerroll once per short restPracticed caster:
+1 to Int or Wis or Chr. Gain an extra 1st level spell slot (regain with long rest). Can make a target reroll a save against a spell you cast once per long rest.
Again, drop the +1. And maybe make it apply to any damaging typed spell? or if it is a single spell make it to always be an option?Focused caster:
+1 to Int or Wis or Chr. Pick a spell from your spell list that does damage to a target. You may freely change the the damage type three times per long rest, each time to any standard damage type you wish. Also, gain a +2 bonus to saving throws to maintain your concentration.
This kind of defeats the point of having spontaneous casters. Further blurring the line to make them prepared-lite won't help a lot. On the other hand it is too much for half and third casters. My counter proposals.Flexible caster
+1 to Int or Wis or Chr. Each morning you may pick one spell from your classes spell list that is of a level you have a spell slot. Add it to your spells known for the day. (This is huge for classes that pick there spells and only change when they level up. It's also huge for multi-class casters to enable them to get to a high-level spell they might not be able to otherwise case. Might be a "must have" for some characters?)
Esoteric Savant
Requisites: Spells known class feature.
Benefit: Choose one spell of each spell level you can cast, that spell can be any spell that doesn't require an attack roll or saving throw to avoid or reduce damage. Add those spells to your class spell list. Add another spell each time you can learn spells known of a new spell level. You cannot prepare, write on your spellbook, or cast these spells as rituals.
Spontaneous ritualist
Requisites: The ability to cast spells without preparation.
When you cast a ritual spell you know using a spell slot, you can meditate for 1 minute to regain a spell slot of that spell level. You add a ritual spell to your spells known, and can learn ritual spells from ritual scrolls and add them to your spells known (Maximum 5 or your spellcasting ability modifier whichever is lower).