When using it together with YUNG's mods, this mod's changes simply don't apply. There is no error in the log, just silently overwritten.

Still an issue in latest forge (.2.0). If I install YUNG's Caves, Simply Improved Terrain doesn't take effect. Interestingly, it doesn't happen with all the other YUNG's mods.

Can also confirm this one happening for me too.

Revisiting this, and am having still having incredible difficulty replicating it.

I've tried all permutations of the following:

• Single Player / Server
• Forge 36.1.32 / 36.2.39

with the following mods:

In all cases, I still see the cave and terrain changes at the same time.

EDIT: to clarify, I still really would like to fix it!

I'm having this same issue.
Actually, after having everything on the latest update (Forge, YUNG's API, YUNG's Better caves, YUNG's Better mineshafts, YUNG's Better Stronghold and I even have Subterranean Wilderness) things seem to work together. I can clearly see the changes made by Simply Improved Terrain and YUNG's mods.

@Pannoniae Interesting. Are you using Fabric or Forge? I have been running the two together on Forge for a while. Just now testing in Fabric, I also had success. Fabric versions:

(Fabric loader is 0.11.3-1.16.5)

Fabric screenshot:

Would you be able to list which mods+versions you have?

Sorry for not replying earlier.
I'm using forge, not fabric.
These are the versions I'm using (please note I have ~100 mods loaded, but tested everything in vanilla biomes):

• Forge 36.1.32
• SimplyImprovedTerrain-0.3.2-Forge
• YungsApi-1.16.4-Forge-6
• BetterCaves-Forge-1.16.4-1.1.2

Also using, but may be unrelated:

• subwild-1.2.1
• Quark-r2.4-312
• BetterMineshafts-Forge-1.16.4-2.0.4
• BetterStrongholds-1.16.4-1.1

Here are some screenshots:
I'm 99% sure this is Improved terrain world-gen

I'm 99% sure these caves are generated by YUNG's mods

@DoctorMeta Oh thanks for the verification on your end! That helps nail down both platforms as working. Now just hoping that @Pannoniae is able to come list their mods and versions so we can compare and find what the root cause of their incompatibility issue might be.

I've narrowed it down to a quite minimal set of mods - http://prntscr.com/19gf38s
With only (almost) all of YUNG's mods and this, I get vanilla terrain.

In fact, just installing YUNG's API breaks it. I forgot to note that this is latest forge. (.1.32)