ATF should be fine with yellow metal. It's base oil, clutch plate friction modifiers, and detergents. Auto transmissions don't have bronze parts either, bronze is only used where it is useful.
Gear oil is stanky-stank because of the extreme pressure (EP) sulfur added. Sulfur eats yellow metal. Chlorine EP additives aren't good for it either.
Machine gearboxes are usually spec'd for something like ISO 32 or 68, non-EP, non-detergent oil.
Gearbox oils usually have anti-foam additives as well; those vary by oil manufacturer, but expect them to be there. You may find antioxidants listed in the fine print too. Usually the better the oil (Mobil vs. Sam's Club), the better the premium additive package. Premium additives add up to end of lifespan savings, as the oils work better for longer.
Boils down to three factors: Oil weight/viscosity, EP formulation, and detergent. Weight depends on the system, use the manufacturer's spec (too easy). EP additives are also MFR spec, depends on the type of gears and application. Don't use oil with EP additives unless it's on the lube schedule. You only use detergent in recirculating systems that have good, serviceable filters (not just a sintered filter at the pump), otherwise the grit stays in suspension to wear out your gears. Detergent free oils allow particulates to settle to the bottom and wash out with an oil change.
I think the theme still centers around using the oil (or a correct interchange) specified by the manufacturer on the lube schedule. Cases where you would need to make a guess should be few and far between.