It isn't enough to read a list of terms, you need to be able to identify them as you are analyzing a game.
You are quite right about this. It can very easily happen that you fall into the pseudointellectual trap and look like a fool
I've never really thought about understanding game design solely through accepted terminology.
The benefit of having terms and definitions that are a bit clearer in definition is that you can communicate better and you will have less misunderstandings. The experience of a game is quite abstract and based on feel, but in order to improve games and give commentary you need to put words on those feelings. Also, I know for sure that there is a "working language" among game developers, educators and gamers. Simply because every domain that takes itself seriously has this. In the domain of games I think it's usually built around features of the games in combination to technical lingo, which sometimes could make it hard to transfer experience from one project to another. But this is just guessing...