My suspicion would be a unicode/ASCII mismatch of the RichEdit control and the data being sent to it. Don't ask me about the specifics here, it's just that the output looks like such a thing.
Lack of unicode support, was fixed by hail-to-the-ryzen in LE and the fix it's included in ZDoom32 as well. I plan to do a release soon BTW but i'm struggling with that farclipline thing (i think it's a cool feature since enhances performance even with very long distances).