As in, making leap a level 3 spell, or making wither a level 2 etc. Since my idea of actually balancing the leap spell #1006 (which, despite allowing easy indefinite flight making the elyra completely useless, is a level 1 spell for some reason) does not seem to be popular, I decided to just change the recipe myself, which I suppose I can do with a datapack, but I do not seem to be able to change the spell level. Meaning, that if a player unlocks the recipe (regardless of how difficult I make it), it can still be shared with other players using a codex and used by players with only a level 1 book

This is already possible in 1.19 in the glyph config. This wont be back ported.