Thanks for telling us about your tests - very interesting! Seems to me you are getting a really thorough testing, presumably designed to identify which areas of your brain may be affected. Whilst a machine could no doubt 'tot up your score' in an instant, I think the results need some interpretation and need to be looked at together with all your previous tests. And even so, there may not be a definite answer! Don't forget also that whatever type of dementia you may (or may not) have, identifying it is only one part. They can write their answer in block capitals and underline it in red but that won't tell you how the illness will progress or any sort of time scale. Neither will your test score show which parts you found particularly difficult.
From the details you gave it seems these tests were designed a long time ago, clearly with no regard to culture or indeed education. Many people would not recognise a bishop let alone know what his pointy hat was called! I can't help thinking the tests are very like IQ tests (perhaps that's what they are based on?) which are designed to test the various different areas of thinking. And I think they are also really hard! I know plenty of much younger people, some with degrees, none with dementia, who would really struggle with some of those questions.
But I think YOU can learn a lot from the tests and how you found them, for example, you were surprised you couldn't recall the long story but it's clear you whizzed through some sections! I imagine that knowing which are your 'problem areas' would be helpful. It would also be useful to repeat the tests after, say, a year to see if there is any deterioration - or improvement!
Finally, I bet if you keep asking yourself the name of that MEP you will remember it eventually. If you keep thinking about the interview, where it took place, the things you discussed, etc, etc. you will probably remember. Usually our memories are still there, we just start to struggle with the 'retrieval' process, but often we can 'cue' ourselves - a bit like you would giving hints to a child: 'What's the name of that animal that lives in a field, a bit like a horse, often brown or grey, begins with a D...'
Keep us posted!