It's not the name.I don't think Level Up is a bad name, and if it speaks to you go for it, but I would personally avoid it because it's already a DnD-adjacent brand. Whenever I hear "Level Up" in the context of a DnD product, I think of Level Up Dice. They aren't exclusively DnD, but they definitely operate in the DnD realm, and they sponsor a number of DnD-related podcasts and the like. Obviously they don't have anything like an exclusive ownership of the term "level up," and not everybody here will have heard of them, but my advice would be to work in a namespace that's not otherwise occupied (for the sake of discoverability, search results, avoiding confusion, etc.).
But that's just how I would do it.
You KNOW its just going to be called A5E everywhere to just embrace it and call it A5E I say.I asked in another thread what you would include in an Advanced 5E game.
But what would you call such a game?
"Fifth Age: Advanced 5th Edition (A5E)" is a kinda working title floating round my head right now, but it's a bit of a mouthful. Needs to be easily Googleable, imply 'advanced' in some way, and also imply compatibility with 5E.
I can't express how much I love 'Apotheosis 5e'@Morrus 'Apotheosis 5e' - it has the benefit of literally meaning what you are seeking to achieve here and keeps the same useful A5E acronym.
Or you could just call it Apotheosis and refer to the cross compatibility with a strapline like '5e Perfected' or '5th Edition Reimagined' - it all depends how much swagger you want to put behind the title to sell it as the 'step up' edition you are going for...