Has anyone ever told you that you come off very entitled and are extremely off-putting? Maybe it is because english is a second language for you? (which is to be respected and appreciated) Maybe I am just inferring it, as you are not intending to be so? Please understand that I’m taking my time to help you. Doing you a favor. Not the other way around.
What you need to understand is that Midi is a nice extra with the SSP. It is not even close to being the most important thing about it. Most of your complaints can be addressed via software additions. However, they are time extensive and there are other more important things, I’d imagine, already on the chopping block.
Midi over USB can have some variations in how it is implemented. The Roland UM-ONE cable takes DIN 5 midi and allows you to plug into a usb interface.
A normal USB cable does usb to usb. I’d imagine the reason you can’t use that with a DIN 5 midi cable would be obvious.
Everything that I’ve plugged into to the SSP with USB to USB midi has worked. The UM-ONE acts as a client no matter what the DIN 5 is plugged into. This is because din 5 midi is not implemented with a host and client facility like USB. This means MIDI works with it, as the SSP sees a client.
Perhaps your other cables are not making this translation.
As I’ve stressed now twice in this thread, if the device you intend to connect to the SSP is acting as a host, it will not work without an interface in between (for example, the UM-ONE).