SureAI

There seems to be an issue with the land field at the entrance of the Shimmering Grove, there's no soil and I fall onto the void into the sea, making it difficult to navigate in this area, I tried reloading and leaving and entering the area back but it won't load.

is that the only area with that sort of bug?
your modlist shows two esm between Skrim.esm and update.esm (those should be the first two)
doesn't have to be the source, but
could be.

Caused by mods, which alter the terrain in the original Skyrim.esm.
This is also noted in our bugtracker.

I see, thanks for noticying this.
Is there any way to note what mod is altering it? Other than the usual one-by-one-discarding?

It's not a single mod that does that, but probably every mod that changes something on Skyrim terrain.
Check out the bug tracker link above. Some users mentioned various mods that caused this kind of behaviour.