I go back and forth on this a lot, but the more I look at it and the more I think about it, the more I'm convinced it is probably not super broken. But dang is it close.
The first thing is that the ritual version is only 1 change to 1 spell, and that change goes away if you do it again. That seems okay, even the very powerful option to not have concentration break is probably okay if it is a single spell.
Though, there is an issue that it is only a ritual, and can be redone many times.
Stacking multiple changes can be done quicker, but it does take at minimum a 5th level slot. Which means the earliest is can be done is 9th level, and it would be their only 5th level slot to do something like make an impossible to break, enemy only Hypnotic Pattern. Which may very well be worth it since they can cast that 4 times a day (three 3rd level slots, then arcane recovery). I think the idea was "but you need to plan what is useful" and forgot that so many things are useful generally, and those are the ones which will get the powerful modifcations.
We also have to look out for stacking with Subclass abilities. It is much easier to do a friendly-fire, distant Fireball as an evoker, because you have friendly-fire baked in. Which means keeping an eye out on future subclasses.
Maybe a good limit for the new spells is that you can only cast them once or twice per day? That just prevents spam. Then again, the real bogeymen for me are Memorize spell (give me an hour to just redo my entire kit, no big deal) and Create Spell which while expensive starts allowing you to customize every single spell you have to be more powerful. That starts at 9th level, and it can get out of control quickly, as it basically laughs in the face of balance. Especially since you can use Scribe spell to move spells from spellbook to spellbook and a group of wizards can trivially start getting massively powerful easily.
