The model itself is fine, in different modeling editors.
This is where the 3D programs "lie to you".
As you've already noticed, the problem is that the normals of several polygons point in the wrong direction. This doesn't matter so much in Blender (or many other 3D programs), because usually the back of a polygon is also displayed with a material / texture.
But most game engines don't have this strange behaviour. Therefore I recommend to enable "Backface Culling" to see the mesh as it appears in Lotus.
To solve the problem in Blender, you can try 2 things.
In edit mode you can run "Recalculate Outside" (CTRL + N) while all polygons of the object are selected (A) and hope that Blender will fix everything (unfortunately this function often fails with very complex objects).
Or you have to select all affected polygons (Backface Culling helps here too) and rotate them manually with the "Flip Normals" command in the same menu.