If Eternabond is applied correctly the edges will be completely flat along the edges AND are not required to be "sealed". However, if there are wrinkles in the Eternabond and voids between the tape and roof, those may have to be sealed.
Why would the Eternabond tape not be flat along the edges? When installing the tape, just be careful to insure it is FLAT without wrinkles. I installed my Eternabond approximately 8 years ago, flat, without sealing the edges and it is still totally attached, sealed, along the edges, and without voids.