Well, here’s how much of each kind of paint ended up in the final product (well, I have a big jar of half-mixed precursor and a smaller jar of final product; this how much paint would be required to use all the initially-mixed paint:
As you have discovered Tamiya’s paint mix suggestions end up looking nothing like the color they are supposed too. You would be much better off to go out and get some Gunze Dark earth as this will mix with Tamiya thinner without a problem.
My problem is that I can’t “go out” and get anything. My nearest LHS is two hours away.
I have to admit that I’m surprised that as popular as Tamiya acrylics are, nobody has worked out (or at least nobody has published) good mixes for common colors like dark earth.
BTW the mix I posted ('cause of all the yellow, I guess) is a little too transparent. To get the right color you need to lay down a dark brown undercoat first.