Confused about UVs, static mesh is completely black

Just remake the mesh with two brushes again, and before converting them to a static mesh, set up the UVs–as opposed to, obviously, converting it to a static mesh and then UVing it. You shouldn’t get that error in the corner (which is probably a case of overlapping faces in the uvs uee4 made), and then afterward it’s still going to wind uo being a static mesh.