Agree about changing too many things. In this case, I changed the sugar cookie and only changed the ratio of the two chocolates. So it's probably 1-1/2 things I changed.Yes, the Fa cookie is less sweet and will add more of a crunchy cookie feel to it. I'm not very good at explaining flavors but I would think that lowering the sugar cookie to 2% and maybe 1-2% Fa cookie would help balance it and make it less sweet. Also, speaking from personal experience, I would only change one thing at a time. I've had times where recipes really get away from me from changing too many things at once.