You have the event history of a non host save, there have fired atleast some events most likely between the autosave and player save, all those events need to be put in also as happened, to do this you need to go through every nations event list and see what events would have taken place.
Also as stated before player save and host save may have irregularities like province ownership and such anomalies, faulty merchants and whatever else, loans or anything else in the game that simply would not be on the host machine but is on the client.
Things like these are what can make a non host save unstable if unchecked, and its an extensive list to go through if you want to confirm all aspects of the save to be flawless.
Still if you go through the event list for all nations from their respective event lists (yes every nation in game needs to be checked), and run the game in SP to 1820 without problems and run an MP test for like PJL said 10 years and the save is stable then I don't see why it can't be used. But do pay carefull attention to any possible irregularties like mentioned above, merchants, provinces, colonists, missionaries, armies, navies, manufactories, fortresses and whatever else like that.
