The display may not be backlighted but it is as bright as needed and as easy to read as any other display in my cockpit.
I have many hours of flying with the butterfly in panel display under any lighting conditions and never had an issue reading the display. I had issues early on with the external rectangular display due to polarization issue.
There is definitely room for some improvement in the butterfly display in my wishlist, making it brighter is not one of them.

Ramy