The way I read this is:
10 orders of Knights Radiant. 10 powers total, each order gets 2, each power shows up in 2 orders.
Each order gets 1 unique powerset that comes about as a combination of the two powers, or is simply unique to that order. This one really depends on if Kaladin's Stormriding is a unique Windrunner power, or something else.
So, Knights Radiant take up 20 of those 30. Or 10, if you break it down to each order's full powerset being a different magic system.
That leaves 10 or 20. 10 levels of Voidbinding makes for another 10. This either leaves nothing for Cultivation (unlikely) or 10 left for her.
Which means, logically, that 10 of the magic systems BS told us about are each of the orders of the Knights Radiant (20 powers, total, but each order only gets one "system"), 10 orders of Voidbringers, and 10 left for Cultivation.
Note, this should only involve magic that runs on stormlight. "Natural" magic, e.g. Axies the Collector being able to change his body and his shadow going the wrong way, should probably not be included in this count, like mistwraiths from Mistborn. They didn't count as a magic system there until they were hemalurgically spiked. If it didn't run on metal, it didn't count in Mistborn. Same with stormlight here. No stormlight, no magic system.
God, I wish we had another series that went as far into its magic system and background as Mistborn did. It would make all of this so much easier.