The trade interface definitely needs some work. Having your charisma character having to do the trading is normal, but they ought to be able to sell from other characters inventories. After all there's already a shared gold pool.
It's a bit harsh to have a mark up from the trader's charisma and a mark down from the character's charisma. It's customary to sell for half and buy at full value in RPGs but in BG3 it feels more like you're buying for more like 4x the sell value. And since you're mostly making money by picking up and selling junk, that's a lot of time picking up and moving around junk in tiny, finicky grid boxes.
