Can the extra Lions predict the postwar treaty balance?

Would a larger force of 13.5-inch battlecruisers produce higher postwar treaty limits or prevent a treaty altogether?

Not confidently from the extra Lions alone; the treaty outcome depends on how their wartime service changes Dogger Bank and everything after it.

The developed counterfactual stops at Dogger Bank because later consequences depend on how the changed fleet performs. Even the opening Mediterranean campaign would not automatically change: Goeben would still face Indefatigable and Indomitable unless deployments differed. A larger pool of 13.5-inch ships creates a chance that one could be sent there. That remains a conditional possibility, leaving postwar treaty outcomes unresolved.