The Albatros D.III (OAW) and the D.V were produced in the same time frame.
The first D.V-s were operational with Jasta 11 at mid May 17,
while the D.III-s (OAW) in June.
The lower wing reinforcement didn't stop with the D.V wing.
The D.Va-s built by OAW, had additional lower wing reinforcements, adding more weight to the plane,
so the reduction of the fuel tank capacity was decided in order to counter the weight increase, without performance compromise.
Considering this, I guess that the problem with the lower wing in steep dives was never eliminated.
I believe that the pilots just were aware of it and flew the plane accordingly, (thus the reduction of wing failure incidents).
The problem was most prominent at the transition from D.II to D.III,
when pilots flew the D.III as if it was a D.II, resulting the lower wing flutter in steep dives.