I have no idea of this concept of acknowledging hits. You get hit or you don't. There are some things I won't tap to either. Guillotines are one because i can generally ride them out.
If I'm working with someone that is ignoring my punches and plowing into me because I'm being a nice guy and lightly tapping them, then the next exchange gets a bit rougher, and so on until they get the message.
But there is a fine line of acknowledging every little touch and knowing that if a technique had been thrown with power and intent it would have stopped you dead in your tracks.
I constantly harp to my guys that you're going to get hit, no one's that good. It becomes a matter of drive and toughness on whether you're able to keep going after taking a few shots.