It turns out that only a single option, CSH_JUNKIE_QUOTES, makes the
error message that I receive:

./zplugin.zsh:34: unmatched "

Earlier I was trying to remove parts, part by part, of beginning of
the zplugin.zsh file, waiting for the error message to change. *It
didn't* (besides languorous movements in line number, after like 5
deletions of large blocks of code; very stable line number) so I then
looked at the Wikipedia page and thought that emulate csh enables
completely different language syntax. Now it might revealed that it
just sets CSH_JUNKIE_QUOTES. Maybe it could be possible to
adapt zplugin.zsh to that option? What in this file can trigger the
message?

https://github.com/psprint/zplugin/blob/master/zplugin.zsh

I might not be able to target emulate csh, but maybe I could target
CSH_JUNKIE_QUOTES. All other CSH* options do not cause problems.

Best regards,
Sebastian Gniazdowski