@Rozzak - People naturally shrink in their old age, something to do with cartilage I think. It's just usually not quite as extreme as what happened to Himmel.
I get the feeling "drunkard priest" was the right translation, both since he was hungover a lot in Ch 01, and to tie in with the final farewell being to pour the bottle on his grave.
(Basically he ain't acting corrupt in any way, but he's a Haddockian drunk)