If I edit building schedule from a CCU, does it sync to other CCUs?

Yes. No matter where you edit the building schedule, it will be synced to all devices that use that schedule. Meaning you could have 15 CCUs and if you edit the building schedule from CCU15, CCUs1-14 will all consume the building schedule change. 

To learn more about the schedule types, check out this article. 
Schedules & Schedule States