What about including a PIXELFORMATDESCRIPTOR member, and adding only the missing fields?
Most of the fields are covered by dwFlags bits with a public definition and documented semantic, then you could include a couple of wine-specific iPixelType values for float formats, and add the fields that are missing next to the pfd in the struct.
This would IMO save one conversion and remove the need for comments for the acceleration / swap / pixel type values.
Also using UINT8/16/32 types rather than bitfields would be better, I don't think we need to save bits here.