As to Fedimint, I only have two technical questions. Say, a majority of minters have colluded to steal user funds, is it then possible to cryptographically prove that:

1. A stealing money transfer was not authorized by any federation users (so it is in fact a steal, not just business as usual)?

2. It is known which exact federation members have signed it off and it is known that all of them understood it's a stealing transfer when signing it?

If the answer to any of these questions is NO then I'm afraid Fedimint is often worse than a single custodian in a way that they may steal money and avoid legal responsibility.

Since it's a custodial solution an enforcement ultimately lies in realm of law, and the problem with group crimes like this is you need to determine who exactly committed a crime here, otherwise a whole group can't be punished (because they all will be pointing at each other, and some of them may be innocent, and then you have presumption of innocence at play).