Because you actually need utf8 support not strip the utf8 byte codes, or try changes chars into something else like codeset library does. Maybe if they where smarted and use utf8.library they solve it.
.m3u8 is actually a playlist format, not an actual stream. I would first look inside the .m3u8 file that how the actual stream URLs look like. Maybe they point to streams in unsupported format or maybe streams are using HTTPS protocol, which might not be supported by Tunenet (I don't know if it supports them or not, but just a guess)?