X Tried to cast ghost companion on you and failed

Does this simply mean the NPC lost focus? Or did I literally resist a GC cast the same way I would resist a stun/curse ?

Ive seen this happen to me also very strange that they cast gc on us like its a negative spell,....

Maybe they have compulsion too?

Speculation.
It tried to cast another GC but has a player selected as a target.

Try to cast a GC when you have a player (or NPC) targetted and see what happens.

I have not looked at this but merely going from memory in early playing days.