"wired solution to connect 2 computers"
"The piece I found was tested with ipad>PC."
I had mine hooked up to an android tablet also.
It's only a simple thing that you want to do, users do it all the time with keyboards.
Most USB Audio Devices have midi In midi Out you connect them with midi cables.
I think you are best to go with the Spanish USB > MIDI <> MIDI > USB as your mind seems to be set on that.