OKi. I think, that a need only use Enca .
I saw, that string functions begins with mb_* (as multibyte) and webhostings are set to utf-8, usually.

Is anywhere developer tutorial. I've forked S9y to my GitHub, at first .

Good morning,
i'd like to help with development of S9y.
But at first:
Czech localisation is in 2 versions - „cs“ and „cz“ (with different encodings iso-8859-2 and cp1250). Why? Is possible convert it into single file - multibyte UTF-8?
I think, that native charsets are deprecated.