Is there a reason you're discouraging the use of this mod?

Hi Ferlonas

It has to do with the underlying mechanisms this mod uses for tree placement - somethingI need to rewrite when I have some time. If you like it, please do continue to use it. But I can't fix minor issues like uncovered ore patches... or more major issues like biter spawns being suppressed until I'm able to rework the mod on a fundamental level.

Turns out that the base game has similar functionality at the moment if you set Tree Scale to minimum, and Coverage to max. Unfortunately that shares the root problem of blocking biters from spawning...despite them appearing on the preview. Very frustrating.

I put in a bug report about this, but it was sadly flagged as "not a bug".

Yeah, trees take precedence over biters, because if they spawned in a forest on a "normal" map it would be an unwanted experience for most players. You have to be careful reporting bugs because it can decrease the likelihood of a fix in the form of suggestions later on.