That is a super beauty. Art Nouveau springs to mind.
As it happens, I have a (leisurely) visit to Maene in The Netherlands planned for tomorrow, but I do not expect this piano to be there unfortunately. Would be a wonderful coincidence and top day if it was.
The linked article also mentions their earlier straight-strung design. I played the concert-size variant almost two years ago. It was really nice, crisp and clear. Quite something. The photo shows that this new curved design is straight-strung as well.
Lovely, thanks for posting this!
Cheers and happy curves,