You asked: " I was trying to find out information of what typical level of THD has a bass/subwoofers configuration as the one you have but it does not exist something about. I think that that information does not exist for a specific room/system.
I checked the James Romeyn Debra, Audio Kinesis Swarm along with google searches sites and I think you're correct, there is no info regarding THD on distributed bass array systems.
I did find an interview with Duke Lejeune, in the Stereo Times
http://www.stereotimes.com/comm081710.shtml
He mentions that when he started designing speakers his goal was low distortion and accuracy. But, when he was finally close to meeting these goals, the speakers did not sound good at all. He was talking about his full range speakers but this may apply to his Swarm system as well.
I think you may be more concerned with THD than I am because I honestly have never perceived any negative qualities that I'd attribute to distortion on music or HT.