I just realized that the map which is the focus of this thread doesn’t highlight suburban or regional rail at all, yet it shows a seemingly impossible RER-/S-Bahn-style through-tunnel that bridges Vendôme (and possibly Atwater Métro) with Centrale, and abandons Lucien-L’Allier.
FWIW, I think with EMU service on exo1 running shorter, more frequent trains, an Atwater station is viable.