Not really a big thing, but it would be nice if rare structures (such as Dark towers) could be detectable by the /locate command.

It should be possible, however, the locate feature requires the twilightforest: prefix on the structure names for it to work, since the locate feature defaults it to minecraft:

Ah it does work (at least "/locate twilightforest:dark_tower"), however none of them show up in the TAB list for some reason (unlike entities or blocks). Not sure if that's an issue with the /locate command itself instead of the mod.

The TAB list is hard-coded into Minecraft itself, which makes it inaccessible to modify. There may be a way to modify the list, but that's as far as I know

Yea the Tab autocompletion is a hardcoded array placed right into the method's return, there's no way to modify it as far as i can tell.

The twilightforest: was just something I decided to add to avoid possible conflicts however I don't feel it's actually necessary and I can remove that if needed.

Ok that makes sense.

There was a Forge issue opened about this here: MinecraftForge/MinecraftForge#3932

Issue appears to be resolved, structures are appearing when tab-completed (this is also on top of the command system being different from before, so tab just goes through a list these days).