The simple rule to follow is no code changes in Production for a scale-out deployment (multiple AOSes), only through release processes. Synchronization task should only run with 1 AOS instance running while no other users are in the system.
If you absolutely must change something as a hotfixing without bringing the whole environment down for emergency cases, only the following could work: Form, Security objects, Menus, Menu items, SSRS reports modifications. If any of them are altered, you have to restore the object on all AX instances to force refreshing them. Also you might have to Refresh Caches. Any other modifications are not acceptable.