Edward vom Hofe established his company in 1867. Here's a reel with the Julius vom Hofe's 1867 patent date stamped on it. Looks to me like Frederich was helping getting his other son in the reel business. Who knows for sure. We weren't there then.
Jim Schottenham and I talked about it. He thinks it was a device meant to keep the two foot screws from coming loose. As you can see, part of it that would hold the second foot screw has broken off. The length of the one screw holding the little bracket is such that it would be close to the inside of the head plate to keep it from coming out.