The language file is named french.par, but treetagger-python try to find a *-utf8.par . I don't know why, maybe the naming convention was recently changed.
To temporaly fix the problem, we should copy (not move, if you want treetagger still work) the .par file, and add -utf8 before the dot. Like that: french.par -> french-utf8.par
Actually, if I download and install treetagger (http://www.cis.uni-muenchen.de/~schmid/tools/TreeTagger/), with a language, for exemple, french, a python call to treetagger fail, because installed language was not found.
https://github.com/miotto/treetagger-python/blob/master/treetagger.py#L135
The language file is named french.par, but treetagger-python try to find a *-utf8.par . I don't know why, maybe the naming convention was recently changed.
To temporaly fix the problem, we should copy (not move, if you want treetagger still work) the .par file, and add -utf8 before the dot. Like that:
french.par -> french-utf8.par
(P.S: Thanks for your work !)