being the type who doesn't like to ruin other people's fun, I always by the swords and beer for the kids in imesvale (spelling).
only this time I found something new...I bought them their beer and went away for a while. I then came back and started the mimic's blood mini-quest, went to the cave and ... those kids are there ?! odd because I usually talk to everyone in the town before embarking on any quests, and I've never seen them in the cave. also, there was only a gibberling chasing them, and the 3 (?) umber-hulks weren't there this time.
Finally, it's the first time my journal has ever finalised the "idle hands" thread !!! (I was beginning to think that would ALWAYS be in my journal as incomplete every time I played)

I had completely forgotten about this quest. In my last three games i haven't even considered the three brats who should no better. Sounds like they get the adventure they're after!

There are a few possible outcomes I believe ..
I gave them either the swords or the beer ..
But that time they were lying on the ground and the Umberhulks were there, long time ago though

Since you put a spoiler tag in the title, I won't put another one here.
I know of three possible outcomes:
Swords + beer : gibberling attacks them and they run away scared.
Swords only : shade attacks them and they run away scared.
PC=ranger + anything : you lose your stronghold

I haven't tried beer only option yet so I can't tell you about that one.

Give them just the beer and the dad of one of them, the fighting man who you see when you first enter Imnesvale, just says something like "So it was you who helped my lad get drunk." I don't think there's trouble, but I've only done that once and that was a while ago so I may be wrong.

They were in the cave in my only game, and unable to stand up. Mimic was the only hostile creature in the caves.

Can some explain how Mimic´s attack affect all your party members even if you would put them all over the cave?

My pc is an ranger with the archer kit, I gave them beer but not swords. I got my stronghold and have done all the quests...