The Stephan Steinbach you mention, born in 1754 in Kell, was my 4th great-grandfather. I descend from him and his first wife, Maria Jungblut. After her death in 1795, he married Margaretha Huwer, as you note. (I’m also related to Margaretha Huwer. In small villages like Kell, one tends to be related in some way to nearly everybody.)
The Matthias Steinbach of my original message was Stephan Steinbach’s grandnephew.