I can tell you for sure that no cheat was done (you can see that my achievements are working as well), the only thing it's Easy difficulty, focused on getting QFtNW and getting islands along the atlantic and Africa to reach America... And forcing every PU that I could afford along all Europe.
Could do even better on normal - but with lot more inflation. Just need to rush for qfntw, and PU aragon and portugal from the beggining. Or castille and portugal. The problem with castille is that they tend to : A - got tons of prestige from taking down the muslims and colonization B - they tend to got biggest armies in europe along with france. Unless they got beaten ofc. So best way to PU them is use spies. When ur castille on the other hand, aragon is quite easy to PU, aspecialy when you manage best economy in the world. I think PU'ing portugal should be obvious (inheriting same culture colonies... instant cores on provinces you don't need to colonize yourself?), same with castille - as long as they did conquered granada. if they did, and ur aragon, you are free to PU them. On the other hand, if ur castille, it is better to ally aragon and let them make their way into italy, and maybe even help them (like - vassalizing pope asap - so they don't get excomunicated, and pope don't get eaten - also makes you the person, that if anyone mess with, mess with the pope, so gets excommunicated by you, as castille got biggest chance of getting big number of cardinals (Biggest christian country because colonizing? Use it to your advantage!))
Anyway not so bad for Aragon.