World Wide Words discusses the word perverb (or portmanteau proverb), meaning a perverse proverb, such as ‘Don’t count your chickens before you can walk’; and portmantreau proverbs, meaning those with one letter added, such as ‘Fine swords butter no parsnips’.
This would be something like ‘Die dümmsten Bauern haben kurze Beine’.
This doesn’t seem to cover the type ‘Geteiltes Leid ist doppeltes Leid’ (‘A sorrow shared is a sorrow doubled’). I think I got that from the amusing Erlangen publication ‘Was lefft’.
Meanwhile, you can test your German proverbs with the Goethe Institut, whose pictures are extremely mystifying.
And Udos Lexikon adds to Feld-, Wald- und Wiesenanwalt Feld-, Wald- und Wiesenübersetzer.