Not sure if you phrased this wrong, or if that's actually what you want, but the sync is only one way, CUCM syncs to the LDAP info. You do not sync LDAP to your CUCM.
Assuming that the userID you have in CUCM matches an LDAP user, it will turn into an LDAP user, and will be updated, any users that do not match, will remain local users.
Iif the userID in CUCM is different from the LDAP user, the local users will remain, are we then still able to edit those local end users in 10.5? I know that in previous versions, we could not edit the local end users after after synchronization ...
In Version 10.x you can have both on CUCM. If you get to the end user page you will see the status of a user. It is either a LDAP user or a local user. both can be managed.
But you are right in older version you could only have one type not both.