I’ve read enough about mendelssohn, but I am an Orthodox jew who keeps halacha to the best of my ability, and the poskim forbade reading his books unequivocally. So I’m going based on that I’ve read “about” him and what all of his students espoused. All of them. Not a few stragglers like the handful of talmidim of other gedolim who deviate from their rebbeim.
All of his students stopped keeping halacha and every one of his children intermarried. That means nothing to you?