When building a simple test program (at least when using libedit's readline compatibility code) it mishandles Unicode characters.
% touch räksmörgås.txt
% cc -I/usr/local/include -DUSE_LIBREADLINE=1 -o tr tr.c -L/usr/local/lib -lreadline
% cc -I/usr/local/include -DUSE_LIBEDIT -o tr tr.c -L/usr/local/lib -ledit
(type "r" then TAB for tab-completion).
Also libedit doesn't really allow me to enter non us-ascii characters at all.
This is different behaviour from gnu readline (see the attached simple test program).
Behavior is the same on FreeBSD 11.3-RELEASE and CURRENT.
SOrry for the delay responding to that PR, to you have your tr.c file here so I can test ?