go back to the Model. I see the Tri’s where you’ve not modeled in Quads.
Eg the window. connect the corners to the corners of the walls to make quads… and no Tri’s will form… otherwise the exporter will Tri those areas to enable a hole in the mesh to be exported…
Most formats don’t like holes in the surface. learnt this the hard way modeling for export to things like Poser or anything by OBJ format.