The whole "They Are Just Go Templates" is a pretty pathetic cop out. Sorry, but it's true. If I'm trying to use Hugo, I don't want to be digging in Go docs at the same time, and as you point out, you can't know things like scopes and what Go variables might actually be available.
And yes, most of the actual syntax is simply not documented.
I subsequently gave up on Hugo entirely and ported my Hugo sites to Next.js, which is in fact documented--and can work well with TypeScript, so complex pages are fully strongly typed, which makes work in an IDE a breeze.
The whole "They Are Just Go Templates" is a pretty pathetic cop out. Sorry, but it's true. If I'm trying to use Hugo, I don't want to be digging in Go docs at the same time, and as you point out, you can't know things like scopes and what Go variables might actually be available.
And yes, most of the actual syntax is simply not documented.
I subsequently gave up on Hugo entirely and ported my Hugo sites to Next.js, which is in fact documented--and can work well with TypeScript, so complex pages are fully strongly typed, which makes work in an IDE a breeze.