How are they generated at run time? Are any parts of them embedded in the source? Allegro itself is pure UTF8, so if you pass it UTF8 text, it'll draw it. If any of the text is in the source file, your editor could be messing with it.
If what you're doing is concatenating bits of text at run time, take those bits of text from a file.
Or if you want to, I think you can use escape codes in your literal strings, ie: "\xCDFEBA01" to encode the utf8 directly into a literal string, and get around the fact that MSVC is broken. But its a royal pain to have to hand encode the utf8 into hex escape codes.