If you peek online at the Mark Morris Dance Group rehearsing Morris’s choreography for a new cross-cultural variant of the 1908 opera “Layla and Majnun,” you see movement that is clean and distilled, marking space in elegant circles and lines. But on stage Friday at Berkeley’s Zellerbach Hall, where the company joined members of Yo-Yo Ma’s Silk Road Ensemble in performing the world premiere of this renowned opera of the East, a cross-cultural traffic jam occurred.