Last week I walked the E9 from Dykhausen to the Dutch border, and I have to issue a warning against your track. As you may know, the general principle for the European Long Distance Trails is to connect existing trails, in this case the Ems-Jade-Wanderweg from Dykhausen to Middelburg, and then the Ostfriesische Wanderweg to Leer, therefore I took great care in following the signposts; I wonder if you ever saw them ??
Here is a list of the errors: In Dykhausen, cross the canal, walk on the northside, and cross again at Abickhafen. South of Hoheesche there is no path along the canal, neither on your map, so you must take a small detour through the wood, Hoher Horst. Cross the canal on Borgweg, cross on L34, again at the docks, and stay on the northside until you reach the foot bridge, where you go south on Ostfriesischer Wanderweg. The E9 follows the Postweg in Holtrop, no detours until you turn right at Grenzgraben. The are no detour on Haupstrasse in Stiekelskamp, just follow the Ostfriesische Wanderweg along the old road, then use Wassergarten. There are no detour in Brinkum. The E9 uses Düsterweg and Buntjer Weg in Brunn.
From Leer and onwards there are no signposts, but still there are strange ways in your track. At Plumenhörn, the gates are locked to the NSG, so there is no access to the dykes. In Weener, the route on the southside of the railroad and through the NSG Püttenbollen is much more interesting than the busy B436. In Charlottenpolder, your track stops in the middle of nowhere. If you turn left on the path, you can cross Wymeerer Stieltief on a footbridge (not shown on your map). This is a German/Dutch crosssing point for several trails including the E9.
As my E9 started in Priwall, I took a quick look at the route, and here are also many errors. I am deeply disappointed.