When my bot, running on Toolforge, reads data from DB replicas, any characters outside of ASCII-7 are replaced by "?" characters, one character for one byte of multibyte character. To solve this problem, I use casting
select cast(fieldname as char) alias
It works, but not for symbols like [1] or [2]. Looks like, this way doesn't work with 4+byte characters, or characters outside of Basic Multilingual Plane. How this problem can be solved?

[1]: https://ru.wikipedia.org/wiki/special:log?type=create&user=Иван+Булкин
[2]: https://ru.wikipedia.org/w/index.php?diff=103627950