Your rainbow looks great. I love purple potatoes. The first time I had them, we were told they were from Puru, but look pretty with a mixture of the small fingerlings. I've never seen macaroons made with purple potatoes. It must be a Canadian thing.
These are definitely lilac, lavender, and purple! Great photo! I’ve sure never heard of potato macaroons, but I’m sure they have to be good or bakeries couldn’t sell them.