I think that you are pretty much there with the green and black. There's something in the tan/brown that I can't quite put my finger on. It looks okay in most places except the left side. That area on the left side under the turret is a bit too large and that may be drawing more attention to it. My recollection and the source photos had the green predominate with the black as a close second and the tan/brown as smaller areas.
I presume you are just brush testing it because we always sprayed and even from a distance, any brushed touch ups looked fairly smooth. In a number of places there's just too much texture.
There's a bit of a sheen on the front and left side. Our colours were dead flat even when freshly painted.
I don't want to sound negative here - I think that you are making good progress, but like you say the bigger models are too expensive for testing on so it's good to work it out here.
Cheers and happy modelling.