Nice Job in getting them to work together.
I for one am not for this ending, while it sounds good in theory, I have a feeling its just a temporary fix until Gaspard throws another tantrum.
I end up executing Gaspard and reuniting B. and C.
Yeah, they ARE all guilty but to me Gaspard only seems to care about getting the throne. At least with executing Gaspard, all Celene has to worry about is Briala and she really is not much of a threat.
I cannot see myself allowing Celene to be assassinated and Gaspard take the throne for the reasons above, but also just in case word got out and The Inquisition knew about the assassination and did nothing to stop it but allowed it to happen. Well at least that is how I play my character, make sure The Inquisition does not end up with stuff that may bite them in the ass down the road.
Over thinking it? Maybe, maybe not. Suppose will see.