Apparently Scintilla's Perl lexer does not recognize regular expression (and other) delimiters beyond code point 0x7E, although these are perfectly legal in Perl (and sometimes come in very handy).
For example this substitution will be not be highlighted correctly:
Note that ¦ is the BROKEN BAR character U+00A6, not to be confused with | or U+00A6 VERTICAL LINE.
A more complex expression like this will throw the lexer completely off track:
s¦(?:<p>)?(<div class="foo(?:bar)?">)(?:<p>)?(\s|<a [^<>]+><!--[^<>]+--></a>)¦<p></p>$1$2¦g;
The same will happen with any other delimiter from outside the basic latin block, e.g. U+00F7 DIVISION SIGN.
I'm using Geany 0.13 on Linux, based on Scintilla 1.75. Other Scintilla-based applications, like Notepad++ or Komodo Edit, show similar problems.