I would suggest doing it the "Find Familiar" way. Where you just have the spell icon, regardless of level. If it can be cast at different levels, as mall pop-out window appears with the different levels you can cast the spell at.
"Find Familiar" does this already, when you cast it, it opens a small bubble-window with the different types of familiars you can cast.
Using that bit of existing UI and populate it with the different spell levels (perhaps even a ritual cast button; or even an active effect (such as witchbolt to keep using the same lightning stream) ) would make it a lot more organised in the hot bar.
![[Linked Image]](https://i.imgur.com/OflRGCe.png)