I have a working Win 3.1 setup (with installed Microsoft Entertainment Pack) on my PCs Dosbox core as well. I'll try mine within the next few days.Yes it's the one. Since then I managed to make it work. I launched Rayman, Doom, Populous etc and it works well. It's a bit slow when there is 3D, even playing on CPU cycles.
By cons my problem now lies in the launch of Windows 3.1 that crash the console. It works on other systems where I have Dosbox. I do not know if it comes from the heart or bad configurations.
But that core (that I linked to) is a standalone from the "older" version and cannot be launched from within the new retroarch.nro, right?