Yes, Lorien is a bit problematic at the current time.
Haldir's Golden Arrow has some nerfs coming in the next patch.
I would also like to see trample immunity done away with and Palace Guards nerfed, Lorien's weakness should be cavalry.
Legolas Knives are fine. Just because he can wreck unupgraded soldiers does not mean he can do the same thing to an upgraded army, supported by heroes. He has practically no army, and gets destroyed by enemy heroes in close.
Beyond the camp bug, I see no problem with Lorien's defences. By the time they have fully upgraded silverthorn archers and towers, you have siege. The biggest problem is the Caras Galadhons, who can outrange siege when put on a platform. I think their range should be brought down a bit.
Ents are indeed too strong right now. I think their weakness should be upgraded arrows, which it currently is, and heroes. The problem is certain damage types deal nothing to them, namely Angmar Ice Arrows and Isengard Steel Bolts. Most other factions can handle them ok with upgraded arrows though, so they really just need to take more damage from Isengard and Angmar, and heroes in general, and they'll be ok I think.