I've added this info to your answer so that other players are also not confused. It's a very good answer that has helped me a lot, especially since you've made this translation (my German is very basic)

Thanks. Looks like it's my mods. I talked to Jens, but to avail. :( Also, Seruk is definitely a part of the original game, I remember seeing him and his quest to steal golden goblins from Urkrass about 14 years ago. Still, I believe there isn't any more information to find, so I'm accepting your answer.