About the rubato on harpsichord, it's done due to physical limitations on the instrument.
AAB would be sufficient
As a general note on ornaments, be aware that ornamentation on a harpsichord generally needs to be heavier than on a piano. On a piano, too heavy an ornamentation tends to be lost in or overwhelm the longer note holding power and can sound very heavy. Adapt to the touch you are using.
But there are no dynamics on a harpsichord.
Without dynamics a harpsichordist needs to use time (and ornaments) for expression.
Am I missing something?
Yes, civility.
Another statement of the bleeding obvious, I'm afraid.
w harpsy there is little one can do to vary tone as it is uniform in sound from pluck to pluck.generally harspy-ists tend to compress and elongate subdivisions of the beat or pulse in order to create variety in the 'tension' for expressive playing. to my understanding, they do not necessarily (or should not be) using 'rubato' as we commonly associate it today.