The way it was told to me is that you had to think of these musical professionals holed up in plague beseiged castles a la Masque of the Red Death / Decameron coming up with increasingly complicated music just to keep themselves sane, however so debauched the music can appear! The 8 Inspanpittas of MS #29987 are exactly that - highly evolved virtuouo instrumental sequences that are best heard played by more-than competent professions at a pace suitable to pushing the limits. Those Oni Wytars / Ensemble Unicorn videos & recordings seem brisk enough in this respect, but I've also heard them played omniously slow as well, which, as you know, is just as demanding. I remember a recording by David Munrow of Lamento di Tristano which was mindblowing in this respect, but where & when that was I can't say, only it might have been a soundtrack for a film about cycle racing (?).

For sure, we will never know, but if musicians can do it now there's no reason to suppose they couldn't back then either - some anyway, but not all, but that's always been the case. Here's David Munrow's take on Istanpitta Ghaetta:

http://www.youtube.com/watch?v=O3Tg_NSmXTU

Lovely recorder, tastefull drones, but the drumming is way off, for more reasons than I might possibly go into here. Suffice it to say that musical imagination can very often run both ways in the quest for the merely authentic. At least Corvus Corax know what drums are for!