The standard ASCII code set only includes up to
number 127. Anything after that on the ANSI table is from the
extended character set and so is
not standard. It is nothing to do with being 'culturally inclusive' as you put it because we're talking about technological standards. While I do agree it would be better if the site was designed to use the extended set, unfortunately it is not.
Regarding changing your username, I can set this up for you, with your go ahead. If I do, you may need to log-in to the forum again afterwards.