Here is the thing, it has been close to 30 years for the mc, in that time he still remembers his love, he remembers the part of tiffany that was his enemy. But the details, the previous context can easily been forgotten. Just because you have a clearly good memorie doesn't mean everyone does. There are lots of faces and names from highschool that no longer ring a bell to some people in less time that the compared ages passed for the mc.
He is a grown man with knowlegde about the present, the future to them in terms of business and the comparable market for the business that the company will deal in. Apart that we know he tried different jobs and hobbies, so he is not a genius but someone with experience.
I have to play it again to be sure, but i could swear that he doesn't remember the test. It's just that after going to university that level of math is no challenge for him. So there again would be an answer that has nothing to do with memory.
Having no memory is not correlative with being smart or not, he is trying to become a better person an sees how he fucked up his relationships, so it is a little easier to not make so many mistakes when your focus is fixing the problems in front of you, be it that you remember them or not.
The argument that the dev gives is reasonable, and there isn't the kind of mistakes that are so big to directly tell the author that he is wrong with his own story.
There are people that can remember with a lot or clarity since they were 3 years old, and there are people that have a harder time recalling memories from 10 years ago or less, so that discussion is one without a real answer that can satisfy your standars.
