So, looks like this will be fixed with Java 7u80, now. However, from what I've been able to tell, that's not planned for release any time soon. The reason I'm bumping, though, is that I seem to have stumbled upon a workaround. With some of the recent changes to font size display in mafia, I ended up on the preferences page while I had the CLI tab open. I saw that the CLI changed font immediately on clicking, and as luck would have it, I had a "broken" table visible. Much to my surprise, the table got "fixed" when I changed font size.
In the attached patch, I've taken the line I found triggered the update, and inserted it into where I think all table output would pass through. I'm not familiar enough with Java or the mafia code to say if this is the right way to do it, or if there are consequences I hadn't thought of. But with that patch my CLI tables now look normal and I haven't noticed anything behaving oddly.
Edit: OK, there is some oddity, in that it seems to get very resource hungry when there's a lot of text scrolling by at once. I updated the patch with a test for table output, since that's the only time the output goes bad.