I had the same issue this summer. You’re right that the speed changes don’t come threw the XML. Yes, the best thing you can do is export a flattened file of the speed change and conform that clip inside Resolve. If you’re not using your hi-res media in Premiere and are working proxy then you can send that clip to AE using Dynamic Linking and option + replace the proxy clip with your RAW file. While you’re at it you can run optical flow before you render out your clip to Resolve. If you have a lot of shots it can take you a little time but at least you won’t have a problem with your edit coming back from Color.
Jordan Mena | Editor | Colorist | Producer
Los Angeles, CA
jordanmena.com