Most of those signs were done be jdenm8. He's really done an astonishing work. If you're interested,
here you can find our discussion regarding these signs and the links to them. I don't think all of them have been included so far because not all areas containing them have been rebuilt yet (and some of them might've been forgotten, don't know for sure).
I know meanwhile it sounds weired because it comes from me again but you still forgot the border at this place (and on others) XDD
Bugs me whenever I see it, too
Regarding federal states, I think it'd be a nice addition to see some "subnational" flags in Germany. Not at the borders like in the UK because that would be pretty strange in Germany and you would hardly see this. In general, flags aren't shown as often in Germany compared to most of the other European states. However, Germany is a federal state so if there's a German flag, often there's a flag of the subnational state as well. Those could be put near official buildings in the capitals of the federal state. The flags can be found
here. Promods also includes some flags near some rest stops in Germany which I think is not very typical. But if you want to do it like this, I feel the subnational flags should be added as well. It would be nice especially in places such Bavaria (where they tend to show their flag more often, I think) or Hamburg ...