It's not desired behaviour, but there's unfortunately no way to change the circumstances that the "on kill" effect triggers - we don't have access to the DD source code. I could have tried to subdue the stress heal when attacking corpses, but it would have likely interfered with the mechanics of some other class mods (and the hero dialogue would still trigger regardless).

Because of the power of the carnival trinkets, would you consider upping the time cost of collecting them at camp?

The Butcher's Circus Trinkets are ported from PvP as faithfully as possible. Some attempt has been made to balance their stats by adding downsides, but they're still ancestor-tier trinkets.

What time cost would be "fair" - 6? 9? Even at 12 cost it'd still be OP.

No matter what number what you choose, anyone playing outside Stygian can quickly and safely farm trinkets by camping twice on long missions and abandoning. Increasing the cost just makes them tedious or frustrating to obtain.

The primary goal was to make the mod as fun as possible, so I haven't done that. You instead get a lucky dip that you're excited to use, and maybe you'll get a trinket for your favourite class. You're correct that it's too strong, but that's exactly why the LITE version exists.

If you want to edit the cost in your own game, the camping file is here and the cost is easy to change :)
"Steam\steamapps\workshop\content\262060\2325415039\raid\camping\ringmaster.camping_skills.json"

I think I will do that, thank you. I did see the light version but I didn't take it seriously. I thought "who doesn't want strong trinkets" but once that ball started rolling I noticed that I was not using anything except those trinkets which sent up a red flag for me.

raw damage on Last Laugh needs to be significantly lower