I think that empty My Favotires after an update is something one can expect since the features may have changed (dropped), but I would still find it more elegant that updates and upgrades leave the My Favorites alone. I suggest you report this as an error, and if the reply is that it is standard behavior, then I would file for a suggestion.

The items in the document \ cyberlink folders from previous versions, IS standard behavior. Cyberlink maintains the various user created masks, titles, particles etc in folder that are linked to the version of PD in which they were created. So far we have seen that most of the user creations worked in newer versions of PD. Maybe also because PD "knows" the version at time of creation and handles the creations accordingly. So, I would suggest NOT to change these folders and/or move any items to other folders nor to the 21 folder.
What I do, just to be sure that I have my created stuff after an update, I make a backup. There were times that a backup was very necessary.....