In PG5, it’s possible to update the initial values of DB elements with the actual online values used on the PCD?

Yes it’s possible to update the initial values of a DB with the actual online values of the PCD.

To do this just open the DB when PG5 is online with the PCD and right mouse click, then select the option 'Upload' from the context menu.

Remark:
In PG5 it’s possible to define the initial values of a DB.
This initial values are downloaded with the application program and are used as first time values if the DB is loaded the first time or after a restore of the program