Edited by HispaZargon: Message moved to this conversation from generic thread titled "List of non-English 'official' quests" for better tracking of this topic.There is not an official US version, that one you linked is an adaptation made by Slev and Phoenix. The hystory is... an Italian user, Legolas77 (aka Legolas Baker), made the very first adaptation of this quest by copying the map from the rear box but since it was incomplete he apllied some changes, featuring a weird rule that the final boss is a statue and can not be defeated so the Heroes have to leave the quest once they realize this.
Also he guessed something about the missing note C, creating the teleport trap from B (which was originally leading to room A instead).
Then Slev and Phoenix created their own adaptation, but they started from the modified map and notes provided by Legolas77. His website is no longer online but it's credited on page 2 of the pdf you linked.
They also added some stats for the final boss which were not listed in the original notes.
I recently did another Italian adaptation of this quest, and changed again the notes including something different in room C.
Please note there is also an exit door in the south corridor wich probably leads to another quest. This map was just a demo and unfinished in my opinion. But again, it would be cool to write a new mini-pack starting from this one.