When I sync a customer or product data sources to the master, sometimes all of the labels get reset to be the same as the names.
It is not possible at the moment. The idea behind that feature is that you maintain the 'meta' data in the Product Master and sync up with that in Analytics. Different labels in the Product Master vs the product data source (in Analytics) would be confusing. Wherever the user looks, the same named fields should mean the same thing (in similar contexts).