In my opinion the settings pages of Java Edition are quite messy compared to Bedrock. Could you please add an option to display the vanilla options/worlds/servers views with tabs?

How similar the design is will be is up to you, IMO just adding tabs of buttons with ellipsis is good enough and you can also keep the tab design of Cloth Config (I think you use that?).

For mod support, well, you could add a keybind that switches between BedrockIfy and vanilla UI, but most good mods add a config access point to Mod Menu anyway.

I've been thinking of implementing something like this (bedrock edition menu GUIs) for a long time. Its an enormous task that will require quite some time and effort. I'll probably end up doing it, but I don't know yet when I'll start with it.