Your question is extremely difficult and I can only have hesitant suppositions.
1 - It is very difficult to understand the legals - in and out- of the XIX° and I recognize my lack of knowledge about.
2 - To have not chosen the legal heir of the French Empire and to have put again the King means a sort of 'coup' , therefore a total modification of the notion of imperial legality.
3 - Indeed the Bourbons always ignored the existence of the Revolution and the Empire. For them after the death of Louis XVI, Louis XVII inherited, after the death of this last it was Louis XVIII. This period of the Revolution, of the Consulate, and of the empire represented some kind of royal amnesia when some usurpers claimed to govern France. For King Louis XVIII his rein began after the death of Louis XVII .
4 - This vision was that of 1814 and I don't see any reason for to have been different in 1812.
5 - Therefore I think that the King would have incorporated to his kingdom all the goods of the empire. For the others, probably, according to their attitude : Those who would have demonstrated allegiance to the King ( Dignitaries as well as the family) they would have benefitted from a certain kindness
In fact I don't see many difference between what happened in 1814 and what would have been in 1812