Silk road and other trade routes probably gave info about the Pacific, but the west coast of South America is unexplained if one continues to insist on no pre-Columbian contact by places like China, Japan and India.
I think you’re right. Plus the monastery in which the map was made/copied could have been acting as a central clearing house for other maps. Hence you get new maps that draw on several older souces, picking & chosing from the best available information. Kinda like the late Middle Ages equivalent of Rand-McNally.