To clarify are you saying it does not work with any of those mods individually? Or that one of those mods is causing a problem?

Also you'll want to provide more detail in order to get support most likely.
forge version:
mod version: (say the actual version not just 'latest')
latest.log:
debug.log:
crash log (if applicable):

If it is one (or more) of those mods causing issues you can determine which is the problem mod with these steps:

1. Remove 1/2 of the mods.
2. See if it is fixed.

• If so, that means one of the removed mods is the problem and you should re-add the mods 1/2 of them at a time until you can narrow down the issue.
• If it is not fixed that means it is one of the still added mods and you should remove the mods 1/2 of them at a time until you can narrow down the issue.

In other words, apply the Binary Search algorithm to quickly find the problem mod rather than removing a single mod at a time.

I can confirm FutureMC 1.12.2 works fine with Aether_Legacy, BetterFPS, JEI, Optifine, HarvestCraft, Quark, and TwilightForest. Latest versions (July 19th, 2020)

Which mods don't work?

Also pretty sure that orespawn doesn't have a 1.12 version

I can confirm that FutureMC doesn't really work well with Patchouli, it stops generating villages.

I can confirm that FutureMC doesn't really work well with Patchouli, it stops generating villages.
Today I tested version 1.16-36-FABRIC of Patchouli and noticed that the generation of villages is working normally.

I think the 'Ore Spawn' mod was this: https://www.curseforge.com/minecraft/mc-mods/mmd-orespawn

What... Future MC isn't for 1.16 or Fabric lmao

I'm going to close this if no info can be given.

FutureMC works well with bewitchment-1.12.2-0.0.22.39.jar from what I can tell.
As well as:
BetterFps-1.4.8.jar
BiomesOPlenty-1.12.2-7.0.1.2444-universal.jar
jei_1.12.2-4.16.1.302.jar
Pam's+HarvestCraft+1.12.2zg.jar
OptiFine_1.12.2_HD_U_F5.jar
Patchouli-1.0-21.jar