my last post didn't get the best editing, which I regret.
The enharmonic instruments in the Habsburgian inventories were
harpsichords. The only enharmonic organ safely known about is
therefore the positive organ in Graz.
Concerning the keyboards of the 13 organs and 3 claviorgana at the
imperial court in Vienna 1706, I could not find any info on compasses.
Vicentino's 'arcicembalo' or 'archicembalo' had 36 notes in just
intonation. These (or similar instruments with 31 notes) were played by
Luzzaschi and Frescobaldi (1619).
When I wrote "Though there seems not to be a direct link between
Frescobaldi and the d'Este-court in Ferrara" I meant his early
years/education. Doesn't exclude links, which are not documented.
And in 1619, however, Frescobaldi played the arcicembalo in posession of
the cardinal A. d'Este, as mentioned.