Author here. I definitely don't feel completely automatic in French, but when having casual conversation I can be fairly automatic if the subject matter isn't too demanding. I think you're absolutely right that without being immersed in French, you will struggle being automatic, especially in all those situations that you only encounter while being in person with actual French speakers.
I think getting C1/C2 certification doesn't really test for that kind of thing, but instead, to my knowledge, being able to communicate increasingly complex ideas in a relatively sterile environment. So, you probably could get fairly automatic when debating about economics or having general conversation or something abstract at home, but in France you probably won't be automatic until you spend a sufficient amount of time practicing all the little things in daily life. This is something I will struggle with to unless I immerse myself someday, but being able to say what you want generally is definitely good enough to at least survive at live decently well. Good luck, sounds like what you're doing is the best possible!
I think getting C1/C2 certification doesn't really test for that kind of thing, but instead, to my knowledge, being able to communicate increasingly complex ideas in a relatively sterile environment. So, you probably could get fairly automatic when debating about economics or having general conversation or something abstract at home, but in France you probably won't be automatic until you spend a sufficient amount of time practicing all the little things in daily life. This is something I will struggle with to unless I immerse myself someday, but being able to say what you want generally is definitely good enough to at least survive at live decently well. Good luck, sounds like what you're doing is the best possible!