So you’re saying it’s not -fully- compatible, then?
My specific concern here would be that most of a wizard’s strength is in its versatility and the A5e wizard appears to have gained a considerable amount of that.
It appears that the O5e wizard would need the O5e spells to remain relevant side by side.
My more general concern is that your solution does not work if the O5e wizard does not like the the A5e spells, because adopting a new ruleset (even a parallel one) requires unanimous consent. At least with my gaming groups.
Do note that this is not a criticism of Level Up, which looks to be, on the whole, a fairly brilliant game. I’ll probably never get a chance to implement it in full, but I’d like to give it a campaign one day.
However, my intent always was to lift pieces of it into my game and encourage players to do likewise. When that time comes, I’d like to be able to avoid rough transitions like the one presented in my initial example.
So, with regard to that example, and considering that I do not intend to force new options on old players, what solution would you (plural) recommend?