Forward-model fitting results for LACES104037-LyC. Observational constraints are limited to the Hα and [O III] emission lines and the LyC-band emission, obtained with subkiloparsec-resolution observations in this LyC-leaking region. The spectral ranges affected by instrumental artifacts are indicated by dashed lines, which show substantial differences before and after the refined data reduction (see Appendix A, Figure 7). We show model spectra at different stellar population ages, where f_esc is adjusted, and the total flux is normalized to the integrated IFU spectrum to reproduce the observed optical spectrum. The LyC-band photometry breaks the degeneracy between f_esc and stellar age present in the emission-line EW parameter space (the lower panel of Figure 5), and only a model with age =5 Myr and f_esc = 0.99 provides a simultaneous match to all observational constraints.