Aperture can’t write its star ratings directly into the image metadata in a way another app can reliably import. A practical workaround is to convert your ratings into keywords first, such as 1star, 2star, 3star, etc., then write those keywords to the files/sidecars. After importing into the new software, you can search for those keywords and reapply the app’s native ratings.

Keywords/tags are the safest metadata to preserve across applications. Ratings and color labels are more app-specific, so they often don’t transfer cleanly. If your new software reads standard IPTC/XMP keywords, using keywords as a bridge is the most dependable method based on the available advice.