@mariusjopen I contacted them and got an reply:
"An issue like this usually has nothing to do with the font itself. All the various quote marks are in definitive unicodes and we don’t have any OpenType code inside Favorit which does any swapping like this.
However a lot of programs (and the Wordpress editor) try to “correct” the type of quotes you write when editing text.
I think something like this could help you disable this default behaviour:
https://www.ironpaper.com/webintel/articles/fix-wordpress-quotes-by-displaying-straight-quotation-marks/"
Do you have any info about such behaviour? I don't want to play dumb with the code :)