When Japan gets changed they need some kinda bonus to their economy that helps them build up their armies, and probably a buff to their units. ATM, all 3 of their uniques are focused exclusively on military.
An solution to this might be to give them some extra production from somewhere with a unique. A change in their UA to accommodate the role of Zaibatsu in Japan would be cool, maybe having something to do with generation of Great engineers and or merchants? I like the idea of giving them a cultural element too though, that will be nice. They just feel so "plain" at the moment.
As for Germany, the only change they really need is a slight modification to their UA. Their UU's are pretty good and appropriate as is. What could be interesting is keeping the current UA as is, but the unit they have a chance of gaining being a random era appropriate UU of another civ. Alternatively, they could also give a small chance of converting enemy civs units maybe?