Some folks, I know Marc Savoy for one, have manual engravers that follow a pattern. Some, like myself and Rusty Sanner, bring our plates to professional engravers. How deep will depend on your pattern and bit, and takes some experimentation so lines don't blur together. I think Randy Falcon puts self stick letters for his.
So the traditional way is to engrave a shallow surface of wood using a template / or a numerical pattern, then fill in with paint and cover the whole faceplate in lacquer / varnish / oil. Am I correct?
Would a simpler appliqué / silkscreening work as well or would it be amateurish?
Not many ever realize that Falcon's logos are not engraved, so I really don't think it matters much. I'd sure be open to trying options other than engraving, I really don't like bringing my stuff in to get engraved, and I like even less the hassle of filling the engraving, all for something that is hardly noticed. There's more important things to spend time and money on.
Some use a paint to fill. I use what is probably essentially a paint, but sold as a faux gold/silver leafing. When I do black fill, I use colored epoxy. Then yep, finish over it.