Yes. Iranians hate their government and want regime change, it’s dubious wether this will help. Most likely it will be used by the regime for more crackdowns and cheap propaganda.
It is dubious wether bombing from afar can even achieve the stated goal (stopping the nuclear program). Hoping it will somehow magically bring about regime change is a stretch.
German law says that if you are in Germany, you can be tried for crimes against humanity anywhere.
After he has served his sentence he may return to Syria to be tried there or the Syrian government may petition for his extradition before his sentence is up. Note that he can not be extradited if he’s under threat of receiving the death penalty at the destination. But all that is theoretical.