The variant Knosalla is also found in various parts of Germany (as is Knosala) as you can see at
http://www.verwandt.de/karten/absolut/knosalla.html but it's not as common as Knossalla. The name doesn't 'look' German and yet it seems to be pretty common there. All three variants are found in Poland as can be seen at
http://www.moikrewni.pl/mapa/ but they're much less widespread.