Is there such a route? As you know Terjit to Oujeft is part of R5 backwards and - according to Cyril's book - halfway along that route a piste leads back up north to Mhaireth (actually not far east of Terjit - on 13°). And from Mh a piste leads NE again to around KM44 on R6. A very long way round.
I presume you are wanting a route direct from Oujeft E or SE to meet R10 somewhere but I've never heard of it and if it was do-able, Cyril would have tried it?
Now I look at the Faraoun 200k map I recall I had the same idea once. If you continue SE down the Oujeft canyon you get to Faraoun and the Oued Timinit which leads NE a few km to a point temptingly close to the Atar-Tidj route (as marked on the 200k). Now I look at it again I must have been planning it on a bike - it only takes a small obstruction to stop a car and there are cliffs all around. According to the 200k, east of Oujeft all looks very complicated: dunes or rock and canyons. There must be a reason the pistes go the way they do.