Those are really large file sizes for flacs and they have a high bitrate which makes thing they might be 24bit flac files. It looks like it's converting them into 16bit ALAC files, so you would be losing some information but they are still very high quality. There might be a setting for keeping them at 24bit on conversion if that's what you want.
If you go into the tag editor in MusicBee and click on the Properties tab you can see what type of flac files they are.