He did have Waterworld included in the collection, he just didn’t count his collection correctly. My guess is he simply remembered that 19 was the total amount of games released in Japan, so he probably just forgot to add in the 3 that were exclusive to North America.
Based on his collection, it looks like he was only interested in getting the Japanese version of a Virtual Boy game if it was released in both North America and Japan. He did also get the 3 North American exclusive titles, though, and I have a feeling that the reason why he got both the North American version of Virtual League Baseball as well as the Japanese version was because of the notable differences in the animation styles of the players. None of the other games released in both North America as well as Japan had enough differences between them to warrant collecting both versions, it seems.
Attached is the picture he included for his Virtual Boy collection.
