Amber headlights have never been common in the US. Therefore, drivers will not immediately recognize them as a "headlight." They may have to think about it for a second. Unfortunately they may be mulling it over while moving toward you at 70 feet per second.

Also, colored lenses absorb some light, so amber headlights are less bright than white headlights. And they "look" less bright too.

The most important function of a bike headlight on the road is to get drivers' attention and communicate "I'm a vehicle". To get their attention, the light should be bright and ideally flashing. To communicate, the light should look like a headlight, not some puzzling yellow thing.