@oldgearguy thanks for your advice and offer!
I will post my new findings in the forum when I find time to tinker again 
I already have established bi-directional nrpn communication between the ambika (shruthi) and the electra and got the change dumps from 0 to 127 for one parameter (used the midi dump tool by urbanspacman). I think I am stuck with the logic of unpacking the parameter values at the moment… But because the whole workflow with the json parsing rules, code implementation via sandbox into the preset is new to me, there could be other errors on my way. I.e. I spend quite some time in the sandbox trying to find some wrong set brackets while inserting the parsing rules…
So it would be very nice, if @martin will ease the sysex workflow in the future
Nevertheless I like to work on this topic when I find time next to making sounds and every discussion here on the forum helps me to understand the sysex stuff and electra workflow better. About the unpayed time spend tinkering with the electra… I think its a question of passion for good music interfaces… in german passion is called “Leidenschaft” which in some way means “creating suffering”… for the greater cause 
I also tried to just use the IXOS software editors for shruti and ambika controlled directly via my ipad touchscreen but the electra really nails the UI with its low complexity visuals and knob feel. I just can concentrate on my ears instead of thinking to much about what’s on the screen… I think @martin really found the sweetspot here