The mountains turn out very accurate but there is litte change in many areas. If you want the battlemap to turn out like real life, you need to make a 1021x1021 map of a small area, otherwise the resolution isn't high enough (at least for a rtw to real life comparison)
Also, you need to make another change. CA cheated a tad and gave the map different gradients so even flat lands will have some curve. One can get around that my turning off the gradients in geography.txt