Most of Halbarad's suggestions won't hep, aren't possible or make it even worse, even though they are well-meant. Mostly it will worsen trolls even more.^^
- making them much more aggressive when being attacked and attack enemy's further away. So that they would also attack early archers like Gildor
This will cause more problems.
1.) You can use one bat to lure them further away and the rest of your soldiers will easily destroy the building.
2. Also it will be way easier for units to run circles, while other units attack the troll, as you have more room to run around.
- add a "rage mode" for trolls, when they do see enemy's for the first time in a long period, they get a boost in speed- and maybe also defense. So that tricking them with e. g. hobbit heroes gets a bit more difficult.
Afaik they already have a similar mode - if they attack units, they will start running. (long period is not possible, but running, if they focus another unit is possible and I think they already have it. At least trolls in the normal game had it)
- giving some of them company by some orcs? Perhaps also so they could heal themselves from time to time by eating an orc
I don't know if it is possible for the trolls to eat orcs. Also I personally don't like the idea of having basically two lairs in one (orc+trolls). Also it caused a lot of problems in the past if troll camps had more than one unit. Quite often trolls bugged in the lair and never left it. THis would obviously make it weaker.^^
- let them hide inside the cave sometimes and come out again when the cage is being attacked
Not possible without bugs. We could use the system of the spider expansion of your castle in Bfme II... But trolls could still be attacked there and they would have a ton of animation bugs. The spiders in Bfme II also have them... they are just so small that you don't see them.
- add mist near to some caves. This would fit very well to Barrow-wights, but could also help trolls to not being seen from far away.
Here my main problem is that it would just look wrong for me. Why should troll lairs cause such a mist? For me it would seem forced and you could still attack with archers and another bat and kill it this way.
Note: I don't say that I am happy with the trolle. I think we need to change things about it... but those changes wouldn't help much.