No I don’t see that message, as you can see in my original post the report says there are 0 non-manifold edges and it has been modelled to avoid that issue however it does say “non-manifold vertices: 1”
Model import settings are as follows:
When I triangulate the mesh I can see the top area probably could have better topology however the lower porch area highlighted, to me, appears like it should be fine
cheers 