I can't speak to SciTE (questions about its UI are better directed to a relevant site or the Scintilla mailing list), but re your desire to restore the file: search the Monastery for threads discussing "encode," "decode" or even "code point."

You can also probably find help in the Tutorials section (based on the inference that you asked your question here because you have some Perl background).

Update: "inference" clause stricken because /me missed relevant input -- "no warnings 'utf8'." Since AM couldn't have updated, it's clearly my mistake. Apologies.