It would seem reasonable to consider word pairs, rather than words alone, since then the notion of positive and negative come into sharper focus. So, for example, on the good-evil axis, tp has one positive but two negative. In another case, Mato gives 'lete' a minus, but does not give 'seli' a positive. In other cases, we find one side represented, the other not: 'moli' but no "alive". I still think the overall result will favor the negative.
As usual, I hold 'unpa'' to be neutral and not a cuss word.