mmm...yes...hfs is actually considering comment files as ansi, always. It has actually no way to know a file is utf-8, because most files lack of the "flag" (a header, actually).
a workaround is to keep comment file as utf-8, and change the template around %item-comment% (and maybe also %folder-comment%) with a {.convert|utf-8|ansi|%...%.}
more: i think we should slowly stop using hfs.comments.txt file format. it was introduced before the descript.ion, that is a de-facto standard, and it has some limits.
limit of descript.ion is that AFAIK it is ansi and not utf-8.
(of course HFS may decide to write utf-8 comments in it, but i don't know how other softwares would behave)
anyone knows about it?