Last time I was in Germany, I had great difficulty trying to do this. As you've indicated, the house number is not like a street address. It's similar to assigning a number to every house in the village, but, I can't tell you if there's any rhyme or reason to the numbering system.
You have to locate the maps made of the village during the time period you're interested in - most likely in the same State Archive where the parish registers are stored. It was a few years ago when I did this, but if memory serves me correctly, you have to cross-reference more than one set of books and maps, which eventually might get you to a map of the house, which you then overlay on a modern map of the village. I had to give up after a while. Of course, I can only speak of my own experience - maybe it depends on the records available for your particular village.
This might be something better suited for a hired researcher, though they are expensive. I'm sure there are others out there who have a better idea of how this works. Sorry I can't be of more help.
Steve
what i did find to be nice... is the house number, when you do find it....
etched also into the keystone above the door....
For some reason, I can get a fairly accurate location from www.msn.maps.com . After that, a local inquiry can usually close any gap...
Dave Fleer
Fleer, Koelling, Kueter, Wahl