Please provide more detail.

You say fossil "can't use unicode character in many places" but you do not
specify what places.  Petr Struc got fossil working for Czech as part of
ticket [30f7206b2].  Are you saying that his changes missed some places and
that addtional changes are needed?  What exactly is not working.

Recognize that the main developers of fossil run on unix (Linux and Mac OSX)
where everything is always UTF8 all the time.  We never have to deal with
goofy windows character sets and have no way discovering or testing for
character set problems on windows.  Everything just works for us. If you
want us to work on this issue, you need to give us more hints.