I thought that you were making the point that sometimes Emma's lies were something that she did in the flow of conversation, and to defend her opinion, rather than an outright attempt to misinform or hurt anyone.

I believe that you have a very valid point. Given that Emma must smooth over her father's feelings several times each day, she might very well be in a nearly constant habit of bending the truth to carry her opinions with him. She can't be very genuine with her father, because he doesn't follow much of what she has to say. So her conversations with others start from a different footing than they would if her most intimate family conversations were with someone who did not require what Mr. Woodhouse requires of Emma.