I remember how BG-2 worked. Although I used the Dragonspear UI++ mod. There were icons/buttons for specific groups of things, like spells, special abilities, and so on. Click one and you populated the HotBar with that category. There were times when you had to scroll through multiple bars worth of entries.
What I'm suggesting is something like a condensed Spells panel. Maybe there's an option to show everything or show what you specify and have others under a separate button. But I am trying to avoid menus within menus.
I can't remember what Divinity:Original Sin 2 did, but I don't remember having an issue with it.
