OK guys, let's have some fun with Nila. We all know Nila really meant gracenote. Ha, ha.
Nila,
Did EAC add any tags to the mp3's before you used MJ on them? When I got that same error message, it was because I had used a tagger that put ID3v2.4 tags on the files. MJ does not support v2.4, only up to v2.3. It chokes on v2.4.
To update the Library to see what info is actually in your tags, go to File, Library, Update, and have it update all fields.
If you use your file explorer to find your new mp3 files, you can drag and drop them onto MJ's 'Playing Now' list and you can tag them from there without importing into the database - IF you have automatic importing turned off in the settings.