I believe brown and amber malts are just higher kilned base malts. I would just input them as base malts with the indicated color level.
The good thing is that the slopes of the base malt and crystal malt acidity vs color relationships are actually quite similar. I would still use the base malt setting for these grains though.
All brewers should note that Roast malts are malts with color greater than about 200L. Below 200L, grains are either Base or Crystal malts. Crystal malts are stewed in the kernal and don’t require mashing since they have already been converted to sugars.