I sent a PM to a Finnish PL coach who's been active for over 30 years with quite a bit of success. I was hoping that he had used this program or knew someone who had good results with it. He just replied, I'll translate and sum up what he wrote.
He started with saying that he knew of the program and that there are supposedly two that are similar, he didn't say anything about how they differed though. He said that the routines first showed up in PLUSA in the 80s (just like you said, Tom) and from what he remembers they were written by Jaska Parviainen. Supposedly it was used by the former WR holder Veli Kumpuniemi. He had some doubts that Veli used it regularly but think he may very well have used it at some point. He continues with saying that he doesn't know Veli well enough to have discussed training with him but he knows Jarmo Virtanen (another finnish deadlift titan) well and he's never used this routine.
He himself does have some experience with the routine though since he used it on some of his adepts. He mentions that he trained around 100 lifters during the 80s and he had them try all sorts of things and this routine is one of the things that were good. He no longer have any notes from that time but he remembers that the program worked well, so well that he wouldn't mind using it on some of his current trainees.
I hope this was of some help.
The routine does look interesting, I'm considering trying it myself.