is it possible to enable diacritic or choose character code page in EPG and INFO page for this TV? It seems diacritic is working fine for menu but not for EPG.
Maybe this depends from local set in service menu? I have it "EU" and all diacritic characters are OK for me. Also might your TV operator sends wrong charset for EPG... ?
Try change country in Channels -> Country and search all channels again. I has this problem, but solved with Czech, Slovanian or Lituanian settings. After found all channels, set language in System -> Language -> Settings to your language.