Changes involving composed attributes should be synchronized from a server instance to another endpoint type without issues. Changes that create or update composed attributes should be written to the LDAP changelog, just like changes to regular attributes.
Synchronization to server configured with one or more composed attribute plugin instances might be more problematic. It might not be possible to synchronize a composed attribute type if the plugin that generates values for that attribute is configured to prohibit external clients from altering values of that attribute.
If server is used as a sync destination in an environment in which some attribute values might need to be composed, then you should compose those values in the Synchronization Server using a constructed rather than attempt to generate them in the server with the composed attribute plugin.