due to the problem with concentration i find alot of stuffs are not being used and hence more party characters defintely helps. for one putting a sorceror? for twinning that may be really great. Btw.. i'm not sure how action surge works in baldur's gate 3. actually i havent try action surge in solasta either. so if action surge grants additional action in one turn that means a fighter with 2 attacks can have 4 with action surge. as extra attacks are based on attack action. so having 2 actions would mean having 2 attack actions. how is it supposed work actually?
You have it correct. Action surge gives you a second full action, so if the attack action normally gives you two attacks, you can have two additional attacks, or use that other action for something else. However, it does not give you an additional Bonus Action.