have to be relatively fluent in Vimscript to pull that off
I don’t think so, using ALE just requires to install the plugin and the external programs that it will interrogate. I know almost nothing about Vimscript.
thoughts regarding Vimscript
From what I’ve seen it’s a scripting language like any other, but one that is extremely specific to vim. The syntax is also quite different from anything else, so I never felt the need to learn it.
Neovim
As a general concept, it seems a good idea, I also know Lua so it would seem to be a logical switch for me.
However, during these years every time I tried it it had some slight differences from vim that made using it somewhat annoying. Moreover, it never seemed to provide such a better experience that made me switch permanently. I’d like to like it, but I never had a reason to.