Interesting results, I have a quick question tho, did you change something in the materials?. Checking the images and comparing them with the textures they are too rough (or less rough I should say) and I don’t see that neither in Substance Painter nor in the engine whenever I set it to the configuration I made even tho I know SP lighting is not as UE4. Values on roughness are higher on your shots, also on B, C and D, the color is way too dark, might be because of the settings you used but again, if you check the textures the values are not that dark, in fact SP has a filter that tells you when it is too dark or bright in order to preserve the PBR rules when textures are authored.
I would be grateful for that info because it interests me to know what you did.