Indeed it does - and I think it's kinda nice that oldies keep coming back!
Well with this in mind I think that the spells would have to be a bit different. Depending on what you ghosts are like of course, but if their magic is now fueled by their Might I would personally argue that PeIm or any other magic to influence the sounds or gestures of the ghosts wouldn't have any game mechanic influence since in essence if they are using their Might it isn't really Hermetic magic anymore. I haven't gotten all through the TMRE yet so it might contradict me in this regard. I stress mechanic because is could see plenty of roleplay consequences of using such magic on the former magi's ghosts and that might turn a battle in favor of the characters as the ghosts might be genuinely baffled or not themselves believe in the strength of their magic without sounds... But wouldn't let said mortal hermetic issues affect the mechanic performance of their might fueled magic. I would also add that if they are spiritual creatures of Might the magic that could affect them should probably be fixed to a specific defining Form (in this case Mentem seems the obvious candidate).
For more of this you might be interested in this earlier thread Hermetic Ghosts - which is of course quite biased by the same of my thoughts.
And btw - magic isn't green! It's the colour of ... (sorry, not at liberty to tell)
I agree - and I must admit that too often this concept of episodic instantaneous action brought on by roleplay mechanics too often might have had me forget that truth. A bit sad bc it robs many opportunities for interesting scenes and descriptions away.