Where can I find that fan group, as I would like to read that for myself?
As far as I can tell (the problem of doing late-night Google searching in an unfamiliar language, with only Google translate and very
rusty, long-unused, memories of reading Njal's Saga
as part of an Old Norse course at university, is that going back through my browser history it's hard to pick up what I gleaned where, and if I was interpreting what I was reading properly!) it was here
; it's only a short exchange, but when the thread took place, four years ago, someone was asking if the stories were ever out on DVD, so even amongst Icelandic fans the releases didn't (to me) seem well known.
This Icelandic comics blog, Hrakfarir & Heimskupör - Verulega slæma myndasögubloggið has a useful page
giving a potted history of Tintin in Icelandic, which mentions the DVDs.
Six stories (presumably, given the date, the Belvision adaptaions) were first released on tape by Bergvík in 1988, as mail-order/ video club selections, with the Thorleifsson dubbed Icelandic soundtrack. These were followed "two years later" (so c. 1990) by a further four. These stories were also shown on Icelandic TV as children's programmes.
It then says that Bergvík went on to release "improved digital versions" on DVD in 2006, with new dubbing by Felix Bergsson and Þorsteinn Backman.
There's no mention of a DVD release in 2005 with the Thorleifsson dub, which is what you appear to have, and my suspicion is that the "improved" release with the new soundtrack was Bergvík's release of the Ellipse-Nelvana series; there would it seems only have been a very brief window in which to get the Thorleifsson DVD versions, which would explain why they had such a mythical reputation, and why anyone searching for them after that date was presented with Ellipse-Nelvana DVDs.