Effects on Critical Hit

[Purudaya]

I'm trying to get a better handle on how opcode 341 works based on the IESDP wording ("change" rather than "add" critical hit effect). I know that it doesn't replace the 2x damage multiplier, but are the effects using #341 otherwise additive or do they replace one another?

For some context, I'm trying to create a passive HLA that grants a stacking critical hit effect each time the player lands a critical hit within a specified time period, with the stack resetting on a miss via opcodes 232 and 321. The kit has access to various abilities that improve critical hit chance, but not Critical Strike.

My modding experience is probably somewhere between beginner and intermediate, so forgive me if I'm missing something obvious here. Can I use opcode 341 to add, say, a stacking +1D6 damage bonus to crits each time the player lands one, or will the effect simply replace itself?

Thanks in advance for any insight, the fact that Cast on Condition doesn't offer "critical hit" as a trigger option has been driving me crazy.