Forge version: 14.23.5.2838
Twilight Forest version: 1.12.2-3.9.888-universal
Link to crash log: https://gist.github.com/KokSaker/1fc67c8f9194219e00046e1d1a618abf
Steps to reproduce:

1. Install Twilight forest.

What I expected to happen:
Built-in advancements loading. Immersive Engineering, Thaumcraft and Tinkers construct mods absence in the pack shouldn't result in an error.

What happened instead:
Built-in advancements not loading.

Mods:

• BetterAdvancements-1.12.2-0.1.0.77
• champions-1.12.2-1.0.9
• deepmoblearning-1.12.2-2.5.2-universal
• Forgelin-1.8.3
• iChunUtil-1.12.2-7.2.1
• jei_1.12.2-4.15.0.283
• JustEnoughResources-1.12.2-0.9.2.60
• MatterOverdrive-1.12.2-0.7.1.0-universal
• Mekanism-1.12.2-9.7.8.379
• MekanismGenerators-1.12.2-9.7.8.379
• MetalChests-v5.1.2+mc1.12.2
• NuclearCraft-2.17a-1.12.2
• Patchouli-1.0-19
• PortalGun-1.12.2-7.1.0
• RebornCore-1.12.2-3.13.12.447-universal
• RebornStorage-1.12.2-3.3.4.85
• refinedstorage-1.6.14
• refinedstorageaddons-0.4.4
• TBone-v1.3.0+mc1.12.2
• TechReborn-1.12.2-2.22.1.979-universal
• twilightforest-1.12.2-3.9.888-universal
• VanillaFix-1.0.10-99

Resolved by 2c21da4 and the mentioned PR being merged.

Known issue, it's not a major problem - as you don't have those mods, it not important that their related advancements don't work.

Currrently, we're stuck waiting on MinecraftForge/MinecraftForge#5255 for us to be able to fix this properly.

Thank you. Glad to see that this was being already worked on.