The Rambam has one knot per chulyah. The Teimanim understand this to mean the chulyah is the wrappings on the outside of a knot. So, 7-13 of that kind of knot. Plus they do a double-knot before the chulyos, as there is a deOraisa knot aside form chulyos.
Alternatively, you could understand the Rambam as requiring the deOraisa knot, and one knot after each chulyah for a total of 8-14 knots.
I don’t see where 5 coud be enough.
Although 2 could take care of the bare minimum one chulyah and you’re yotzei. Still not 5, though.
5 knots can be made consistent with the Raavad and with Rashi and Tosafos, as I wrote earlier.
The Gra has 5 knots – 4, 4, 4, 1 chuliyos between them. Again, chulyos with knots.
Keeping 7-8-11-13 is shakier, as would be 7-9-11-13 unless you have Raavad chuliyos. Then you are specifically NOT following Rashi and Tosafos, who say that what we were wearing in their day wasn’t chulyos.
The reason why I don’t smell the chulent cooking in my decision is that a number of chassidishe rabbeim (and a poseiq) as well as two Litvisher gedolei haposqim of our generation believe that’s what the Ari meant.
I assume we can agree that the Ari would do things with a consistent hashkafic (ie Qabbalah) and halachic position. Not chosheish style. So, if all those posqim understand the Ari that way, it is apparently reconcilablem and not a chulent of practices based on conflicting positions.