Removal at its best is Magic's premier tool for catching up when you fall behind. But, to crib from Patrick Sullivan a bit, when destructive interaction is priced to move in every color, the game can start to revolve around such effects. Reflecting on this spectrum, and looking back again at the deck I built, I think I may have been off-base advising more removal
per se. An observation of your cube is that the interaction's power level is bimodal but skewed:
Most of your removal is premium, format-defining interaction spells that would easily see heavy Standard play. Examples: Prismatic Ending, Unholy Heat, Fatal Push, Inquisition, most of the burn spells, KCommand, Collective Brutality, most of your countermagic. Having some of these cards is a way to pull synergy drafters into a splash for premium removal which unlocks new synergies, or they provide direction to newbie drafters, as you mentioned when discussing rate-optimizing strategy. So I like some of these, but this is the majority of your removal.
The minority is kinda bizarro interaction that is an obvious plant for a synergy deck but (IMO) is weak enough that even the synergy deck would only pick it if it's late pack 3 and they're short on interaction. Examples: Raven's Crime, Flame Jab, Forbid (which I'd guess is difficult to pull off), Foul Play, Wretched Confluence, Collective Defiance.
So 90% of the power of your interaction is located in the cards themselves, and not in synergistic interactions between cards. A drafter optimizing for rate will get a ton of good removal, which disrupts the opponent's synergy deck. And since the best class of cards
vs. removal is proactive rate cards that get their money even if Doom Bladed --> my Kroxa/Saga deck.
So... what if you kept the same as-fan of removal, but imposed efficiency hurdles on some interaction to push the average removal power towards the lower end?
For example, what about
Magmatic Sinkhole over Unholy Heat? You remove the ceiling of Heat mercilessly dunking on Oracle of Mul Daya, but preserve the ability to catch up vs. the opponent's Tombstalker. Fatal Push to
Strangling Soot achieves a similar move. Pacifism or that Amonkhet sacrificey version over Prismatic Ending. I've played many cards in this vein in my
low-power synergy cube and my
Eldraine Remixed format. Especially in the former cube, where I needed to consistently answer Aura'd-up monsters, while still allowing the Auras player to get their jimmies instead of getting blown out.