Ah cool yeah that all makes sense. I guess the problem is non-linear difficulty of multiple homing enemies. 3x pink spiders is more than 3x as difficult as 1, but it is any homing enemy that effects this not just individual types. An exponential weight multiplier would probably do something. Also that they will persist and follow from the previous zones. Tracking homing enemies close to the player and including it in the new zones spawn weight to reduce it etc. Give you a hope of running away when under pressure from them with a slightly easier zone.