I've been testing several trim related on 1.20.1 with forge 47.2.0 and verified this by making a mob pack with only this mod.
Some material effects don't seem to function at all. I tested this with iron armor and the coast trim, for the netherite and lapis I used a stone sword.

• amethyst, even with a full armor set trimmed doesn't give night vision
• copper, even with full armor set trimmer doesn't give any swimming speed boost
• Emerald, seems to have no effect at all
• netherite, doesn't make item fire proof but does give fire resistance
• gold does not make piglins neutral

I'll update to 47.1.3 and see what's up (this mod doesn't support newer forge versions than that)

amethyst, even with a full armor set trimmed doesn't give night vision

It doesn't give the potion effect, but it gives the same brightness boost

copper, even with full armor set trimmer doesn't give any swimming speed boost

If it's not doing anything, then it's a forge issue, not my mod

Emerald, seems to have no effect at all

It's a fresh world, of course it won't have an immediate effect as it increases existing reputation by 10% and 0 increased by 10% is still 0

netherite, doesn't make item fire proof but does give fire resistance

Verified that it still works

gold does not make piglins neutral

Verified it still works, only 1 piece is needed

So in conclusion everything is working as intended and any problems are caused by forge or other mods