I don’t think this is anything to do with y the issue here is that snowball stemmer is used in English. It has edge cases
I have been considering using ispell instead. Since you are a non-English install its very likely the English stemmer is a bad choice and you should just go with simple or a language specific stemmet.
It will require mucking with the install a bit.
Long term I am thinking of doing all the stemming and stopword in our ruby process to avoid all the magic done in pg.