This doesn't answer your OOC questions, but IC the Ministry has the Committee on Experimental Charms - I've played a member there before and figured their job was to receive petitions about new spells, try them out, and then kick them back to the creator if there were too many side-effects/unintended consequences so they could keep refining them. Like I imagine there's a way to get your spell approved for general use and if you haven't passed that bar yet, you could get in trouble for teaching it to other people or using it in public/etc.

If mods want to do something like this OOC, there's a mechanic in D&D that might be useful: wild magic surges. Jack's playing a "wild mage" in his current game and it's basically a sorcerer who doesn't have control of their powers yet, so they have random acts of magic happen occasionally.