All I can say is "it is not Perl's fault".
Using Windows-1252 encoding is weird, but not incorrect. If your desired content type is text/html, then the whole set of Unicode characters is available for you not only in UTF-8, but in any encoding supported by the browsers. Both HTML::Entities and Encode can do the necessary mapping of Unicode characters to Entities which are then plain ASCII strings and understood by the browsers.
I'm not going to defend the source code running this site either. I consider it pretty stale, but you can let software rot in about any programming language. In Perl, of course, the software will continue to run and run and run, as years go by.