That's not the application. ML accelerated modeling allows for instantaneous iteration. It dramatically speeds up creative engineering and scientific work. You take the final product and run it through a classical simulator as a final QC - though in my experience (in a different domain, but similar principle) the ML model outputs tend to be smooth/continuous and ≈98% MSE accurate. Of course you need to carefully train your models to span the input space, but for finite element/finite difference modeling this is relatively straightforward.