For what it's worth, the first two steps in your lookup would come naturally to a native speaker- it's a suffix formation similar to e.g. "cleanliness" and "friendliness".
"Curmudgeon" itself is interesting, because while it's not particularly common, I actually think a lot of native English speakers would recognize it because it's got a lot of character- for some reason, the way it feels to say and the way it sounds almost has some of the character of the meaning.
Especially as it’s not a very common word a lot of non-native speakers need to look up. Probably also a few native speakers.