No, really. Considering that it isn't actually possible to squeeze through some trees, even though you can in most, I would suggest putting some sort of 10 use Burning Hands (2) device that vanishes on reset into the quest, near the start. A Brush Burner or something. It would allow you to cut through rather than having to metagame the need for a mage with AoE spells.
Problem: Pwrgmr noobs would take scrolls and save them instead for clearing gnolls.
I have never been fully stuck. Always found a place to get through.
Same for me as for Paha. Always could fit through somewhere. It might not look like it, but usually you can get through.
Maybe I dont quest enough to find every bug though.
Most of them you can, but sometimes nowhere works. It seems to be especially problematic as I'm playing a halforc and thus have a larger character model than most players. As for using them on gnolls, it's not that big a deal. It's a low damage (2d4) cone that wouldn't be gamebreaking as not using it would block you more, and the gnolls won't be one-shotted by it. I know this is supposed to be in line to be fixed, but until then, this would be a simple solution.
It is a bug. I hope Mort will fix it one day.
There already is that low level 2-4 Ziggurat quest where you get the Mask of Pittiless Flames with 20 Burning Hands to battle the zombies.
That too disappears on resets and is hardly game-breaking at all. If you want to attack Gnolls with a flamethrower you'd be either mad over overconfident. Regular attacks are still better.
So please, just do this.