All you need is one bard with the Song of Compulsive Cavorting.
They patched that out. CC (like Song of Compulsive Cavorting) only works once. Then the redcap becomes immune. Nobody's talking about it. All the people saying, "just use bard cheese" are now wrong. In fact, all the Haernhold bosses are now immune to that song after one use (except for the one warrior construct that is completely immune to it from the start). Some of the story bosses have the same ability.
Without that immunity, you can also stunlock most melee-capable enemies in the game with critical blocks. You don't even really need a bard.
Also, drunk stacks aren't that big of a deal. There's a quest item you can get that's wearable and makes bards immune to getting drunk (no stun). As long as you never complete the quest, you have the ultimate bardic headgear. Drink all the elven wine you want.
So can you expand on why a single optional incredibly difficult challenge dungeon makes a game awful ? How is the rest of the game if you ignore that single dungeon ?
Because I'm stuck. Permanently. I can't finish the game! I can't even cheat my way out since the only trainer I can find has trojans. I might be able to hack my savegame to change everyone to an Outlander temporarily and beat it that way, but after killing off not one but 5 horrible dwarven constructs with 2500k+ HP each, I do not feel like grinding through that stupid redcap. Everything I have done up to this point is completely negated by the fact that the devs trapped me in this dungeon with a fight I'd have to respec/reteam to beat, and I can't respec since I can't even get to the statue at the start of the dungeon that let's you respec without going back to the guild. I can't hire new adventurers to deal with the problem either. I can load an old save from before I beat Gaerwyn, I guess? But I am not sure if I can beat Gaerwyn with a team that's also set up to beat the enraged redcap. The redcap fights are so tiresome that I don't even want to bother with it. Beating Gaerwyn took maybe two hours of retries until I finally got it right, and I had to remove one of my rogues and add a practitioner I didn't really want to use that was custom-built just for that encounter (and the stupid mage construct that has some of the same problems as Gaerwyn. Actually, the mage construct is worse).
It's like going to the movies to watch something that's maybe a great B movie or a mediocre Hollywood flic, only for some random smelly dude who hasn't taken a shower in a month to jump on you from the seat behind you and teabag your head. Whatever I saw on the screen up to that point is no longer relevant. I'm leaving the theatre, getting my money back, and filing charges by that point. My perception of that movie would be permanently ruined.
edit: I found a savegame unpacker for Bard's Tale 4. I'm looking through the file in a hex editor to see if I can find a way to alter my party location to sidestep the redcap and finish the game. So far I've found:
and
I replaced that data with data from an older save in the Old Adventurer's Guild. So far, no luck! Loading the edited, repacked save still puts me in Haernhold.