[El Gato]

IIRC, Both the CH-47 and the V-22 have the engines cross coupled to both rotors/props. Thus something would have to take out both engines or the transfer mechanism, for there to be a need to autorotate. Plus the V-22 can glide, not well, but better than any pure helicopter. Landings would be messy if you can’t get the engines titled up. Probably survivable though.

[Lexinom]

Yes the mechanisms for twin rotor are rather complex, esp. with the cross-coupling. That's the price paid for the better performance I suppose.

To my knowledge, no intermeshing rotor configuration has ever had an accident due to a breakdown of the synchronization mechnism (blade collision). Not to say it hasn't happened or isn't possible.