“In Rav Folks book on engagement it is not proper to compliment one another, so why do u think it is acceptable on a date?”
I would not presume to speak for Rav Folks (?) or any other rav. But the fact that he personally feels it is not proper, does not make it the absolute halacha. Many rabbanim bring their own personal biases to their interpretation of what is proper. There was a rav who was extremely makpid not to speak to women too much. One day he met (I believe it was ) Bruriah the wife of Rabbi Meir, and asked her how to get to a certain town. He actually said “What road should a person take in order to get to Lyddah(I think that was the name)?” She immediately chided him, reminding him that he preaches that it is assur to speak too much to women, and that he SHOULD have been more brief and said, “By which to Lyddah?”
The point is, not everything said by a particular rov who comes from a mindset built on his own life experiences, is necessarily the halacha. It may be, or it may be his own specific hashkafa. Anyone who believes that an engaged chosson and kallah should not compliment each other, is possibly a person who never believes in giving compliments, period. There are plenty of people who are emotionally withdrawn and unaffectionate in that way, and it breaks up a lot of marriages.