What do you mean by "dupe the trade"? Two of any, say, haste potions or precisely two haste potions, both of the splash variety? Either way, very doable. Xp change is also easy enough.

Dupe the trade I meant they could get the trade twice in the list iirc, just for different prices.

Got it. How does changing it to not get the same combo (potion effect and type) ever sound?

Also, should I make lingering and splash potions more expensive than their base counterpart since they take additional ingredients to create?

Makes sense, though if it's random idk if it may cause them to have very different prices, unless you overlap the prices (note: can't remember if it was random).

Yes prices are random so that'll be kinda tough. I have a working version of no duplicate potions if you think that's enough. I haven't messed with xp yet.

And why does the function for adding potions to the cleric (line 133) take a player as an argument and not use it? That's been there since it was first uploaded.

I don't see an option in villager trade data to mess with the amount of xp given, so I think the best I could do is hook into the event and summon more xp orbs.