Phase transitions, cusp cascades, and a Feigenbaum-type universality in the Aether fractal family

We resolve all three open problems stated in Bird (2026b) concerning the non-holomorphic fractal family zₙ₊₁ = K z_n exp(Im(z_n)) + c. (OP-A) We compute the cusp-bifurcation locus K_cusp(N) for N = 2,…,7, showing that the locus peaks at N = 4 (K_cusp ≈ 11.047) and ceases to exist at N ≥ 8: the cusp is a finite-depth phenomenon with no N → ∞ limit. (OP-B) We prove that the Class C subleading expansion A(K) sqrt(ln K) = 2R sumₙ₌₀ⁱⁿᶠ D_n / (ln K)^n, with D_n = (2n-1)!! / 2^n, is a Poincaré asymptotic series derived from the erfi expansion (DLMF 7.12.1), with D_1 = 1/2 proved exactly and verified to 0.66% at K = 10^100. (OP-C) We study the one-dimensional imaginary orbit yₙ₊₁ = K exp(y_n) y_n + delta as a parametric map in K and locate its period-doubling bifurcation sequence K_1,…,K_9. The ratio sequence r_n = (K_n - Kₙ₋₁)/(Kₙ₊₁ - K_n) converges to 4.671 at n = 8, within 0.03% of the Feigenbaum constant delta_F = 4.6692…. The cascade accumulates near K_acc ≈ 14.9048, well below the phase-transition threshold K* ≈ 25 of Papers 2 and 3. This two-stage structure identifies K* as a secondary geometric event inside an already-chaotic regime, placing the Aether family within the universality class of one-dimensional maps governed by Feigenbaum renormalisation. An analytically exact non-holomorphic distance estimator is also derived, exploiting the Exact Decoupling Lemma, and produces publication-quality boundary renders at any resolution.