Make sure your printer supports printing unicode characters. Try updating your drivers and going into the settings and turning on truetype fonts for printing or a similar option. As far as I know, Courier uses ASCII.
Typing :h printencoding turns up:
If 'printencoding' is empty or VIM cannot find the file then it will use
'encoding' (if VIM is compiled with |+multi_byte| and it is set an 8-bit
encoding) to find the print character encoding file. If VIM is unable to find
a character encoding file then it will use the "latin1" print character
encoding file.
When 'encoding' is set to a multi-byte encoding, VIM will try to convert
characters to the printing encoding for printing (if 'printencoding' is empty
then the conversion will be to latin1). Conversion to a printing encoding
other than latin1 will require VIM to be compiled with the |+iconv| feature.
If no conversion is possible then printing will fail. Any characters that
cannot be converted will be replaced with upside down question marks.
Four print character encoding files are provided to support default Mac, VMS,
HPUX, and EBCDIC character encodings and are used by default on these
platforms. Code page 1252 print character encoding is used by default on
Windows and OS/2 platforms.