Well, I don't claim to be the ultimate authority on this, but I've never heard the term used for relationships other than first cousins. Perhaps you could have double half-cousins or double step-cousins, I'm not sure. But since we are all connected back there somewhere, I would expect that any two people could probably be related to each other in a number of different ways, and we could drive ourselves crazy trying to assign some terminology to every possible different combination.
Nevertheless, I see that if you Google the term "triple cousin" you get hits, and there are probably some of those posts that agree with your interpretation. I didn't spend a lot of time looking at them, and can't say if any of those authors know what they're talking about.