This is not stolen money, they have committed no crime, and they have not been accused of a crime.

They are accused of A) violating sanctions placed on Russia and B) attempting to circumvent sanctions. Since these are part of the European sanctions programme, sanctions are the punishment. These sanctions are put in place after an investigation by the EC.

Except the only courts they can challenge this in are in Brussels and the sanctions ban them from traveling outside of Germany.

The ECJ is located in Luxembourg, not Brussels. You also do not need to physically travel there to start a court case. You can either attend digitally, or you can simply travel there since travelling to- and from a court case is exempt from any travel restrictions; this stems from the same right that allows a prisoner to attend their court case or to sue, despite not being allowed to leave prison.

Oh btw, another fun tidbit: any contracts signed before the sanctions may still be paid with funds from the frozen accounts. In other words: if he signed his lease before the asset freeze, he may freely use those funds to make rent. German social programmes can help take care of food.

Again, these sanctions certainly aren't fun, but if he or his kids are going to starve because of them, that's entirely voluntary. They can still make rent, they can still feed their kids. That's why he's still posting away on X instead of living under a bridge. These are sanctions designed to prevent asset flight, not starve someone.