Yes, CullAi supports photos in RAW format that are supported by the host macOS version. For details please check Apple documentation for RAW support on your macOS version. Ideally RAW photos for which you can see preview in Finder and are viewable in Apple Preview app, should be supported by CullAi.
Here is a list of macOS versions specific support at the time of writing this article, please check for newer version support by searching for same on Apple support portal:
- Digital camera RAW formats supported by iOS 14, iPadOS 14, and macOS Big Sur
- Digital camera RAW formats supported by iOS 12 and macOS Mojave - This should be supported in macOS Catalina also