IMO what a reconstruction may have challenged is the checking routine. Which ironically enough could have given more time for Madeleine to go missing without being observed.
LOL I'd thought of that, as well.
Either they really did check on their kids at regular 30-45min intervals, with some passing by within 10-15 mins of each other), in which case the reconstruction might have been able to prove that some fat geezer had, in the meantime, got stuck in the window and they couldn't possibly have not noticed (the window was out of the line of vision for those heading towards the main entrance and was largely hidden behind a tree... but those are details).
Or, said geezer was slim and agile but would have needed more time to get through than the supposed timings allowed. Conclusion: their checks weren't as frequent as they'd said.
If that were the case, then indeed it would have left more time for someone to get in via that window.
If the police were only interested in entry via the window, the elephant in the room is whether or not the police had verified if someone could have got in at any time via either door, and not the window as the parents had originally assumed.
Isn't that a bit self-defeating?