You may consider it a superdestroyer, but it's ussualy just called destroyer.
It has the firepower to deal with Lucifer and (most likely) Hades, as well as ability to properly engage the Sathanas, so it's likely that it's called a superdestroyer in propaganda, but it's technically a destroyer, just like Lucifer (notice the SD Lucifer, not SSD Lucifer).
I doubt that superdestroyer is an official classification at all, it was just a term coined to describe the Lucifer and later applied to Hades (was it called like that at any point in ST?), which means "something the size of a big destroyer, but so powerfull that a normal destroyer won't stand a chance".
If the Raynor was introduced by the time of FS1, it would be called a superdestroyer, but I think that at the time of FS2 the term might have went out of fashion.
I think that UEF would have called the Raynor a superdestroyer at the beggining of the war (it has Lucifer-like beams, is large and very powerfull, so comparing it to Lucifer won't be much out of place), perhaps some civilians still do it. It all depends on how you define "super".
In short: it isn't technically a superdestroyer, but somebody unfamiliar with military may call it like that.