You did reply me on the Youtube video. Thank you very much for the feedback. I managed to make it successfully work with one of my machines by following what you exactly advised here.
I first installed the 184.108.40.206 trial you pointed on a second Windows 7 machine. The activation worked flawlessly, even though I already activated once previously with a 220.127.116.11. I then copied the "Roland" installation folder from the "Program Files (x86)" folder into a second XP machine, which has never seen an SCVA before. And guess what? It worked. I'm still annoyed by the "Trial mode" pop-up windows but it works (I now only have to figure out a way for those pop-ups not to exit a fullscreen game on that machine, but that's another story).
Now I only have to wait 14 days to see if the time limit still triggers there too (on the first XP machine it's a dead end however, still getting the "expired" message, but that's because I already "tried" a few years ago).