Does anybody have a good seat cover supplier they can recommend?
I tried interior-innovations and their covers were full of defects, even the replacements had defects.

There is leatherseats.com- very expensive.
and Rides (who are on the forum), but they seem like interior-innovation under a different name.

 

I've used Leatherseats.com before for my FC, but that was about 15 years ago and they weren't as pricey back then. Cost me about $500 for a deal they had advertised here on the forum back then. Great quality leather, they fit perfect, easy enough DIY installation and they still look & feel like new 15 years later. I order them in the black upgraded leather (whatever they called that), and my seats were the S5T2 high back style seat with the integrated headrest.

I ordered a set of tan leather seat skins for my FD recently from RX7.com early in December, as I found they had the best match to the OEM FD tan leather in terms of color & texture after getting swatches from all the places the OP mentioned. Ari at RX7.com informed me of the potential long wait when I ordered (he's having supplier issues like everyone else), but no worries there since Ari doesn't bill your CC until it ships - class act business!