Thanks for pitching in, Ajay!
I am getting stuck at his part of your explanation:
Second, we move to "after the Berlin Wall had been demolished", which is a dependent clause. Had been demolished requires another event in the past that happened after demolition, but such an event is not here anymore. Note that main clause is present perfect action which is continued in the present.
Doesn't the acclimatization of east germans count has another event that follows the destruction of the wall? Going by that logic, shouldn't we use past perfect tense for destruction of the Berlin wall?