Given how OTL Milan alone was supposed to be enough to exchange for Lorraine, why would the Duke of Lorraine get Lombardy and Piedmont (and potentially Genoa)?
I also don't understand why Genoa is being passed around willy-nilly. It was an independent Republic.
Genoa is a small state with already little true indipendence so will be easily annexed by some powerful neibourgh who want or need sea access. In any case annexing just a part of Genoa to Milan-Piedmont for giving it sea access can work very well.That was not the only option, if the duke of Savoy was not willing to exchange his lands, so including Piedmont, for Naples and Sicily, there were other options. One would be the duke of Lorraine & Bar, not sure if under that Scenario, it would just be Naples. Savoy, like Austria, was much more interested in the duchy of Milan. IOTL Savoy ultimately gained the kingdom of Sicily and bits of the duchy of Milan (most of the duchy of Milan went to Austria), after a few years they were forced to trade Sicily for Sardinia.
A real issue with these treaties, was that they, France and England-Scotland were making proposals to redraw the map, without the other parties, most notably Spain and Austria present. Spain did not like, that foreigners were carving up their empire. Austria is a bit more tricky, yes under this second treaty archduke Charles would inherit Spain and the colonies, but the French presence in Italy was matter of concern for Austria.
The interests of Savoy or Lorraine were far from the main concern either; IMHO in theory, an ATL provision in an ATL proposal, which would have transferred the Riviera di Ponente* from Genoa to Piedmont or Milan-Piedmont, seems entirely in line with the OTL treaties. (*= not the entire Republic of Genoa)
The Duke of Lorraine would get Piedmont only because Savoy need to swap all his lands for Naples and as Piedmont can not go to France annexing it to Milan is the logical solution...
In alternative the Duke of Lorraine can have Naples while the Duke of Savoy will have Milan (and maybe Corsica for having a royal title). Netherlands, Sicily, Sardinia can either stay with Spain, go to Austria/France or be given as compensation to the loser of the Spanish crown