Hi Falko,
good catch - there is indeed a naming mismatch: the german preference is named "Lieferant" (since 2018) and the tab is named "Bezugsquelle" (since 2017).
The question now is (and I'm a bit reluctant to start this discussion): is "Lieferant" better than "Bezugsquelle". The idea behind "Bezugsquelle" was that sometimes you get some wine which you didn't buy but got it as a gift.
The not working preference is a bug which will be fixed with 22.09.1 - indeed it is already fixed :)