Improvement of effective Erdos-Wintner theorem for Zeckendorf expansions

We revisit the effective Erdos-Wintner theorem for Zeckendorf expansions. Drmota and the author obtained a uniform Kolmogorov bound whose error involves $T\sum_{j>L-2h}|f(F_j)|$, which assumes absolute convergence of the linear tail $\sum_j f(F_j)$. We remove this assumption. Grouping the transfer matrices in pairs and working to second order on the logarithm of the product, after extracting the common linear phase along the dominant direction, yields a quadratic tail $T^2\sum_{j>L-2h} f(F_j)^2$, or, in a flexible variant, the split tail $T\sum_{|f(F_j)|>1/T}|f(F_j)| + T^2\sum_{|f(F_j)|\le 1/T} f(F_j)^2$. Either form requires only $\sum f(F_j)^2<\infty$.