That doesn't look like BetterFps failing, more like Chiseled Me. Hard to say whether MultiMC is involved.
Some patches were not applied to class TileEntityBeacon:
- <replace GETSTATIC net/minecraft/item/EnumDyeColor.WHITE Lnet/minecraft/item/EnumDyeColor;>
at dev.necauqua.mods.cm.asm.dsl.ASM.checkMisses(ASM.java:182) ~[chiseled-me-1.12.2-188.8.131.52.jar:?]
at dev.necauqua.mods.cm.asm.dsl.ASM.doTransform(ASM.java:129) ~[chiseled-me-1.12.2-184.108.40.206.jar:?]
at dev.necauqua.mods.cm.asm.Plugin.transform(Plugin.java:40) ~[chiseled-me-1.12.2-220.127.116.11.jar:?][/pre]
Have you tried with the default launcher for comparison?
Okay, I did a little further investigation, and it's a conflict between Chiseled Me and BetterFps - they both modify TileEntityBeacon, so currently you can only use one or the other, and it's a known issue: https://github.com/necauqua/chiseled-me/issues/48