I’m not enough of an historian to argue, but Oberlanders probably encompass more than Hungarian, more like Prussian, which I believe would include the former Czechoslovakia and Austria. But then we get back who who is a Yekke, only German Jews or Austrian as well?
And in the real world moving affects minhagim, or else we’d all have the same nusach, same headgear etc.
Even of someone is meticulous with his minhagim, when he moves and the new local Rabbi institutes a new tekanah he must follow it, and he may not do differently than the tzibbur in many instances.