While many worlds interpretation provides a complete and thorough description of the state of quantum systems (including observers as quantum system), it doesn't provide a prescription for how the physical state of the system is related to the experience of observers.
In many worlds there is no significance to any operators on the Hilbert space unless those operators happen to be part of the Hamiltonian (which is Hermitian) which is used to determine the time evolution of the universal wavefunction.
Otherwise there is no special significance to Hermitian operators. One might say that many worlds doesn't give a prescription for how observations happen so there are no such thing as observations in the many worlds interpretation and thus there is no need for observables.
To answer your question directly
Given that observations are not treated differently than other events in the Everett interpretation, how does this relate to observations being hermitian operators?
Since observations are treated no differently than other events (unitary evolution through the Schrodinger equation for all events) there are no observation so there is no relationship between observations and hermitian operators.
Because MWI doesn't give a prescription relating our experiences to the physical states I see it as being a fundamentally incomplete and scientifically insufficient interpretation of quantum mechanics. I would think that anyone who says otherwise is implicitly or explicitly adding additional postulates to what is usually understood as the many worlds interpretation, that is pure wave mechanics.