if your party is full when you recruit wyll and send him to camp, dismissing a party member to add wyll makes him "level up" to level 1, resetting the merchants. I guess this could work with the others too... now, I don't know why it didn't work with lae'zel and shadowheart, I'm almost certain they gained enough xp to get the "level up" prompt just by avenging them...
and, since I had the occasion to check it, the bug I reported
here showing that jergal's outline stretches to infinity at some angles is present on all maps, not just the temple camp. I haven't noticed it on any other character so, unless it has something to do with its particular status, I guess there is something wrong with the model ? I can't go and outline the problem this time, it's outside of my skillset...