Just so I'm not answering the wrong question, you are talking about the "Language" field that contains, for example, "eng" and not the language of the track title or anything, right? The field's set based on the language of the associated work (for example, Hva kommer fra havet now displays as "nor" because this work is listed as having Norwegian lyrics), and, unfortunately, many recordings in the database don't have any work to retrieve that value from -- see this one I pulled from the same search for what the typical recording looks like. That's one of the things I'm focusing on fixing as I work through my library, but it's slow and I'm not going to go too far away from my own stuff. If you want to put in the time yourself and help everyone out, I'm sure we'd all appreciate it.
As for the embedded covers, I'm sure it wouldn't be too hard to write a plugin for, but I don't think Picard supports it currently. Until someone writes one, I'd just say that, unless you have a particular reason to embed the images, most players I know of recognize images in the folder just as easily -- sending the music wirelessly to a TV is probably the most common thing I can think of that would require the embedded images, though I suppose some handheld MP3 players might also need them.