Eh. Eeeeeeeh.

As a fellow german, I think it's very thin evidence. 'Keil' is just such a common word, especially in more 'old-fashioned' settings, and the other languages lack such a connection of the terms from the Quest and the location. Unless the term used in the Quest and the name for the House of the Crooked Coin align in other languages as well, it's just as much likely as any other theory regarding what the 'wedges' might be.