Let's get terminology straight. It makes a difference.
A catch, by definition, is taking possession of a ball that is in flight (i.e., before it touches the ground). Taking possession of the ball after it strikes the ground is recovering. In this scenario, there is no 'catch' at all. There is a recovery.
A valid signal is one given before the ball strikes the ground (and meets other criteria). A signal given after the ball strikes the ground is an invalid signal (there are other things that make a signal invalid, too, but we're only concerned here with the fact that the legally kicked ball struck the ground before it was possessed). Whether valid or invalid, if a signal is given, the legally kicked ball may not be advanced, whether caught or recovered; the ball is dead when the catch/recovery is completed, whether the catch/recovery is made by the signaler, or any other player.
A catch of a legally kicked ball following an valid fair catch signal is a fair catch. If the catcher is then contacted significantly or tackled by an opponent, the opponent has committed a foul for an illegal block or tackle following a fair catch.
A catch of a legally kicked ball following an invalid fair catch signal is NOT a fair catch. It is just a catch. If the catcher is then immediately contacted/tackled (without the contact also being a personal foul) by an opponent, there is no foul by the opponent. (Note: The catcher is protected by UNR Late Hit rules.)
Following either a valid or invalid signal, a "catch" of a legally free kicked ball made by the signaler behind Team B's 25 yard line gives the ball to Team B at the B-25. (If another B player catches the ball, that is NOT a fair catch, the catcher is not 'protected,' and they get the ball at the spot of the catch.)
Following either a valid or invalid signal, a "recovery" of a legally free kicked ball made by any player of Team B behind Team B's 25 yard line gives the ball to Team B at the spot of the recovery.
A signal given after the ball strikes the ground is an invalid signal, and rules pertaining to a recovery of a kick after an invalid signal apply (ball is dead, no protection, no advance).
A signal given after the ball is in possession by B is an invalid signal, and rules pertaining to a recovery of a kick after an invalid signal apply (ball is dead, no protection, no advance).
It is very important to use correct terminology when discussing rules with other officials, so as to not confuse the conditions of the discussion.