None of that is a problem if you accept MWI. The mental benefit of MWI is that instead of worrying about both entanglement and observation/wave function collap

None of that is a problem if you accept MWI. The mental benefit of MWI is that instead of worrying about both entanglement and observation/wave function collapse, you only need to worry about entanglement because what Copenhagen describes as collapse is really just entanglement of the observed system with the observer.