I think there would have been a definite air of disbelief amongst the Scoobies. Probably some comments made in the same vein as Willow's to Angel in Pangs. The Scoobies didn't know Cordy, not in Sunnydale and especially after she left. Anything they said would be based on their preception of her which was never the whole truth. The Scoobies own personal hang ups with Cordy would have played heavily on what they thought of her new exhalted position. Willow, depite having moved on with her life with Oz and later Tara, I think would have still held an ill placed grudge against Cordy for 'stealing' her first love from her (even though Willow stole him back) and the years of bullying she received from Cordy. Xander I think would make alot of meanish jokes but secretely would be both happy and proud of Cordy. Buffy, I think would kinda react the way Angel reacted when he found out Spike had a soul. Like Cordy was stealing her thunder somehow.
I think all their reactions would be irrational and heavily influenced by their high school years, in fact I think they would react as if they were back in high school, with more than a tinge of immaturity.