1. SysEx feedback is a special case of sending specific SysEx messages from MDP2 output to input, where they can be processed with StreamByter rules. This is implemented.
2. Get state from a device is possible in several ways.
3. Additional SysEx variables have previously been requested, but is a low priority right now. With StreamByter and SysEx feedback, you can configure as many additional SysEx variables as you need, and the two existing variable cover the preponderance of use cases. https://mididesigner.com/support/requests/ The Roland Jupiter X(m) has the similar Roland architecture, and it is possible to edit everything with the previous MDP2 SysEx capabilities. (I have not updated my Roland layouts to take advantage of more current MDP2 capabilities.