When playing with mods that add their own world type (for example, Modern Beta or BetterNether/End), the create world screen doesn't include their respective modded world type addition(s) in its selection, limiting folks who play with those sorts of mods to just vanilla's world types.

It's a known issue, because of the modified Create World screen, there is no good way to use the default world presets, due to using the vanilla Create World Screen for this, and even if I used these default world presets, modify the vanilla presets screen would be harder.

I see :0
I do hope it can get worked out soon, this whole thing's pretty exciting as a fellow Legacy Console fan :3 Take as much time as you need to figure that out

I hope so too, but it will probably take a while

I managed to add this in 1.2 version, thanks for requesting.