The most obvious example - just right click to pick up half of some stack of LE.

[13:33:16] [Render thread/INFO] (Minecraft) [STDOUT]: adjusting balance for 22 §aLiquid Emerald
[13:33:16] [Render thread/INFO] (Minecraft) [STDOUT]: trying to cast 22 §aLiquid Emerald to emerald valued item
[13:33:16] [Render thread/INFO] (Minecraft) [STDOUT]: 22 §aLiquid Emerald is EmeraldItem{amount=44, unit=LIQUID_EMERALD}
[13:33:16] [Render thread/INFO] (Minecraft) [STDOUT]: Adding 0stx 44¼² 0²½ 0² emeralds to inventory

WynnItem has cached that the stack has 44 LE, but after right clicking, it should update this cache.

thats the behavior i observed in #1548 and also something I need to have fixed for #1994 to highlight items. i already experimented a bit and it seems like a possible solution is to store the ItemAnnotator in the ItemStackMixin and re-annotating the itemstack on copy if it is applicable else test all annotators.