Fine job you did there.
Just slap the Ebond over that and call it good. Roller it down. Sounds like you followed Ebonds instructions about removing the old as best you could. No sense going crazy. If you can only get 15 years out of it that's still pretty good isn't it?
One of the things I did when an edge somehow detached and started peeling off was just put another piece of Ebond over the top or under the loosened portion. That extended the covered portion of the roofing material to an area that hadn't had tape on it before.
I'd put it on so the new stuck down tape edge was either upwind of the old tape, or up slope...if you get my meaning. But these are ideas to use only if your newly applied tape wants to lift off the roof too soon.