Your math is incorrect: 4 * 5 = 20 ...
You don't gain Pillars/Pends of your elements in wins, so assume 81 cards lost, not 63. If you keep 3 quanta sources per deck, that's a total of 9. In 3 decks you'll probably be losing about 36/45 quanta sources. If you have to play the same amount of matches - like when your drop from 283 -> 220 cards left - you're left with no way to get enough quanta sources.
Plus, most decks use more than 12 quanta sources.
Also, your solution would make allowable conversion less.