Proper modellers will chose paint based on either the colour description on the side of the tin, or compare the lid to a reliable photographic source.
I'm not a proper modeller.
As far as I am concerned, bauxite is a sort of rusty colour. Looking at photographs, the stuff never seems to be the same shade between different wagons. When I brush paint, I used Humbrol 70, Brick Red. For this wagon, because it is larger and I wanted to get on, a can of Halfords red oxide primer has been sprayed on.
The results are, to my eye, pretty good. The paint finish is smooth an even. Those corners have come up nicely so the filler works well. It will be finding a more permanent spot on the bench.
Anyway, the colour looks fine to me. Eventually it will become filthy and no-one will notice. Well, except those who spend all their time worrying about such things and don't do any modelling...