There's no "convert format" tool for images in MC, so the answer is no, it's not possible.
As I've said, I've zero experience with RAW files of any nature, but, if RAW files contain EXIF, IPTC or XMP metadata, I would expect your chosen conversion tool to preserve these in the new jpg file. If that's not the case though, there is a way to work around this...
1. In MC, go to Tools > Options > Library and Folders > Options and untick "run auto import in the background"
2. Close MC
3. Move your RAW files elsewhere on your hard drive. The idea here is to break the file links in your MC library.
4. Do your conversion. Keep the file names the same, and save the converted files in the same location as the RAW files were before you moved them.
5. Open MC, list the RAW files concerned (the ones that are now actually jpg files, but MC is looking for RAW files and can't find them) select them all, right click, library tools, find and replace.
6. click the 'select none' button, then find Filename in the list and select it. In the find field, enter .RAW and in the replace field, enter .jpg, click OK.
7. select all files concerned again and perform an "update tags from library" on them to write the tag info to the files themselves.
8. Turn auto import back on by reversing step 1.
Job done.
If you want the original RAW files to remain in MC, you'll need to go through the entire process again, switching the jpg and RAW files while MC is closed, and then importing the jpg files in the normal way. The tag info should be saved in the jpg files themselves and will be picked up and read during import.
It may be worth checking that the setting for "save in file tags (when possible)" is activated for any image file tags you are using to be sure that they get written to the new jpg files in step 7.
I know it's a tad convoluted, but at this time, I think it's that, or nothing.
-marko.
