Ah talmid,
It isn’t double talk, it is the accepted lomdus. The lomdus of what is happening when a person is m’gayer is that he is accepting upon himself the yoke of mitzvos. He is agreeing to be bound by the mitzvos and punished by Hashem for not keeping them. That is what being Jewish means.
While we tell a ger some mitzvos before he is megayer, we don’t tell him about all of the mitzvos. A person can be megayer without knowing any of the mitzvos and the geirus will still be valid as long as he understands that he will be bound even by the mitzvos he doesn’t know about.