Posterior distributions of lens potential parameters obtained with models exploring the role of the PSF. The dash-dotted green line distributions correspond to the Cluster+Exp model (i.e., similar to the green model in Fig. 6) using the true supersampled PSF used for simulating the data (top left panel of Fig. 11). The solid red line distributions are showing, for reference, the blindly submitted model Cluster+Exp+Lumweight (i.e., the same model as in Fig. 6). The dash-dotted and dotted red distributions, also obtained with the Cluster+Exp+Lumweight model, use a supersampled (interpolated) version of the data-resolution PSF (bottom left panel in Fig. 11) or the true supersampled PSF, respectively. The main result of this comparison is that biases in lens model parameters are most reduced only with a combination of a more accurate PSF and a model that can capture magnified cuspy features in the source.