Einstein radius (θ_E) distributions. The blue histogram shows the ∼93 000 lens–source pairs with a flat θ_E distribution between 0.1″ and 2.0″. After removing artifacts, ∼80 000 clean systems (orange) remained that still follow a flat θ_E distribution. The green histogram shows the final ∼50 000 mock LSNe Ia passing our brightness selection and restricted to θ_E > 0.5″, which delimits the region of interest in this study. Of these, ∼48 000 are used in the training, validation, and test sets with a balanced number of doubles and quads.