This page serves as concept for adding additional CopyQ command line switch to print and read texts in UTF-8 (i.e. without using system encoding).
Every time the bytes are read from a command (standard output or arguments from client) the input is expected to be either just series of bytes or text in system encoding (possibly Latin1 on Windows). But texts/strings in CopyQ and in clipboard are UTF-8 formatted (except some MIME types with specified encoding).
When reading system-encoded text (MIME starts with “text/”) CopyQ re-encodes the data from system encoding to UTF-8. That’s not a problem if the received data is really in system encoding. But if you send data from Perl with the UTF-8 switch, CopyQ must also know that UTF-8 is used instead of system encoding.
The same goes for other way. CopyQ sends texts back to client or to a command in system encoding so it needs to convert these texts from UTF-8.
As for the re-encoding part, Qt 5 does nice job transforming characters from UTF-8 but of course for lot of characters in UTF-8 there is no alternative in Latin1 and other encodings.