"lighthearted fun" in the same way that "add gargants" was constructive criticism.
The point is, this "test" signifies nothing.
Let us take a look at this. The test supposedly checks whether or not a fictional race is a Mary Sue race. Now, the question is, what are you supposed to do with the result? One of the best SF backgrounds in existence (Iain Banks' Culture universe) features a race that is so blatantly Mary-Sue-ish that you could pretty much tick all the boxes in that little test, and it still manages to be compelling and a good playground for the author.
Then let us consider the Shivans. Even they score 10 points on that Test, making them dangerously Mary-Sue (They could score higher, if we knew the canonical answers to all the sex/procreation stuff the test asks about), yet noone ever said "Welp, those Shivans are faaaar to boring to be taken seriously".
Also, the term "Mary Sue" is not vague at all. I think it's actually rather well defined for something that is on Tvtropes.
Trying to pass off a test that is supposed to check for the presence of a given trope (one whose presence is implied to be negative) for lighthearted fun is at best misguided, at worst trolling IMHO.