The fight was one of the last ones in my play through. I was lv4 and walked in there as a group. I had to fight and I won without cheese. Only Gale went down twice, enemies really like him.
Enemies like to go up, just cast or attack, then shove them down. If they survive they will come up again so you can repeat. Enemies are dumb. The invisible guy did not do AoO or special attacks, another one cast silence, I just walk out of it and cast.
The fight is fine and it is absolutely possible to win without cheese.
There are many warnings that this can get hard, like the scout on the bridge, the red dragon and how they deal with the flaming fist.
The game is fine and it is good to have some more difficult encounters sometimes. Plus this fight is totally optional, you do not need to kill them to get to the next chapter.
But you get very useful stuff from them.
I think you ignored the actual problem as stated, which is the game is set up to strongly encourage you to do this fight before you'd be ready. They need to either have Lae'zel back off a bit with this shit or have her come in after you get more chances to level.