When you get to Darkest Hour, all errors in there are mine. Feel free to curse my name at will and yell at me for my mistakes. It's been awhile since anyone tore apart my work.
To me, the weakest point in
Darkest Hour is when Frosty "examines astrally the disc and determine it's not the real disc" and the PC are supposed to follow her to find another one.
The end of the adventure clearly suggests the real artefact has been hidden in an alchera for the last 12,000 years (more on that later). In that case, the disc the PC recovered in Germany is the one and only "real" Disc of Phaistos. That is, it is the Disc found in Phaistos in 1908 by Luigi Pernier's team. So, at that point, the contract is over: they recovered the item. Frosty never warned them that the Phaistos Disc may not be what she's actually looking for.
I think the Debugging entry should at least have addressed the possibility the runners would renegotiate their contract at this point.
She was obviously aware of that possibility, since she does check the disc, immediately get to the conclusion it is not the artefact she's seeking, and she was taught a very specific ritual to locate the artefact using one of its copy. The Phaistos Disc has been on display in the Heraklion Museum for 150 years. So you'd think at some point, for the cost of one airline ticket and one museum ticket, Ehran could have checked before hiring the first runner team.
Besides, it's quite misleading and confusing to have both discs called the Phaistos Disc. The real artefact should be the "Visoko Disc" ou "Visočica Disc". Unless Phaistos, where the copy was found in 1908, actually was the place where the artefact was created.
This based on the assumption that real artefact stayed in the alchera for several millennia. If it the Disc found in 1908 was the real artefact, then it would mean someone stole it and replaced it by a copy at some point, and somehow managed to hide it in an alchera. Since the entrance to the alchera was buried for all that time, it had to be either someone with the ability to open a temporary entrance to the alchera (if there was a permanent entrance, it would have shown up during Frosty's ritual, like the pyramids did) or the ability to move through earth (which would make Celedyr a prime suspect, more-so considering his interest for ancient writings).
Also,
Darkest Hour states the Atlantis was destroyed in 10,000 BCE as gamemaster information. This is consistent with Plato's writings, but not with Ehran's exposé "Humans & the Cycle of Magic" (two different versions on
SR website and
Amurgsval). That would be rather significant, since, besides the fact that Ehran spread disinformation, this was, as far as I know, the one and only source for the length of the cycle of magic. Though in my opinion the 3100 BCE date was much more interesting to connect the late Fourth Age to Ancient Egypt, Newgrange site in Ireland, the Cucuteni-Trypillian culture in Ukraine, and the eruption of Mount Mazama/Crater Lake
Funnily enough, in the adventure background given to the Gamemaster, it is said that after the theft of the Sextant of Worlds from DIMR, Ehran "realized that someone else was beginning to collect the keys." As far as we're told, the Sextant was stolen by runners paid by Aztechnology, while the Disc is in the hands of Hermann Meyer of the Faustus Society. But the entire point of the runners going after Malcolm Carrela is that Ehran doesn't know who have the disc. Had Meyer be in league with the azzies, it should have been stated somewhere. It instead says that he died "for the cause" as it's put, which rather suggests he was only loyal to the Faustus Society. Meyer's assassin, was recruited in Bogota, and tasked with casting the blame on the azzies, but we never get to learn who hired him (and how did they know Meyer had the disc). So Ehran's conclusion that "someone" is collecting the artefacts based on those two theft is wrong: there's no connection at all.
As a side note, I wondered if the whole plot on copies of the Disc was based on the "Vladikavkaz Disc" story. In 1992 fragment of a disc similar to the Phaistos Disc was found in Vladivakavkaz, in North Ossetia. There are only a handful of pictures, since the disc itself disappeared in 2001.
For additional fun with an Indiana Jones cross-over, Vladikavkaz also happens to be the easternmost point reached by the German army during WW2. Among the units involved in the operation was the 22nd infantry division, which was scheduled to invade Crete but moved to southern Russia instead, and later finally went to Crete (where its infamous commanding officer general Müller became known as "the butcher"), and later in... Yugoslavia. Familiar places ?
EDIT - rearranged paragraphs order