Is this talk just a convention?
It's all about mental context, my friend. If in your mind there's a (silent) conviction that you see, you act, you were born, you will die, this is you etc. - if your subjective experience is like that - then for you there is Self. Even if you don't use the word "I", there's is still belief in I in your mind.

If in your mind there's a silent understanding of how things work, how mind works, and how illusion of I is generated - then for you there's no "Self" or "No-Self" - you clearly see how it really is. Even if you use the word "I", there's no belief in I in your mind.

All talk is conventional, because "conventional" means we assume we are more or less in agreement what each word means. What matters is your mental context.