The results from ISS are much more pessimistic than you say, suggesting some irreversible damage besides the reversible changes, but I am lazy now to search links to the research articles. The weakening of the skeletal muscles is not the worst, but the deterioration of the heart muscle.

However, the research done on mice on ISS suggests that the undesirable effects can be mitigated by creating an artificial gravity (i.e. rotation) lower than on Earth, e.g. of 2/3 of Earth's gravity.

The failure scenarios for rotating spacecraft need not be more severe than for non-rotating spacecraft. For instance if 2 or more spacecraft, which can be also used independently, are connected with cables to enable them to rotate around the common center of mass, if everything is designed carefully the failure of the coupling system should not have any other consequences than the loss of the artificial gravity and from then on the failure risks would be the same as for non-rotating spacecraft.