Residuals for the stellar mass when a model trained on one simulation is applied to the other. On the left, we apply the model trained on τ-delayed SFHs to the test set of the simulations performed with the Dirichlet prior. On the right, the model is trained on Dirichlet SFHs and applied to τ-delayed simulations. We colour code each simulation with the fraction of the total stellar mass, computed from the true (inferred) Dirichlet SFH, that is formed before the inferred (true) value for t_i from the τ-delayed SFH. We find a significant average underestimation of the stellar mass for the parametric model applied to the Dirichlet simulations, which correlates with the fraction of mass formed before the inferred starting time for the star formation.