Transparency is apparently a net positive according to your logic

just to be clear, I think this only in terms of high level army building, but in terms of new nullification effect using transparency as part of the attack, it is probably not going to be favorable very often (although it would be entirely possible to null an enemy unit and give them an advantage because of it)

transparency should be denoted more visibly in some way

(actual transparency on the piece)
I think this is how it will go, or some variant of this, but not sure yet if all the ghost-like units will do this by default or if it will be reserved for nulled units (since a ghost could also be nulled, it may provide more visual information to have the transparency be nullification indicator)

some cool ideas

some of the suggestions you made are interesting to think about. idk if they would shuffle their way into this particular update, but maybe some could be added eventually. A bishop+knight champion seems to be a blindspot to me, thinking about it now it seems obvious and not sure how I never made one.