The "Balanced" difficulty is INCREDIBLY UNbalanced. I have a level 5, well-balanced party, and I still get my shit kicked in 9 out of 10 times.
Yeah, it's not a problem of the game, I can tell you that.
If people are managing just fine in Tactician, you are just doing something poorly to have your ass kicked "on the regular" in "Balanced".
And Story mode remains an option, anyway.
P.S. It would help at least offer some context, to know at what point of the game you are crossing these "unfair" encounters, anyway.
This would read like a textbook "I fought the Githyanki patrol at level 2"... Except you claim to be level 5 with the entire party, so it can't really be that.