I think the only "level" you should really care about and isn't on that list: being fluent enough on all systems, APIs, libraries and infrastructure you are con

I think the only "level" you should really care about and isn't on that list: being fluent enough on all systems, APIs, libraries and infrastructure you are connecting to or using so you ultimately do not really care all that much which language you are programming in, on which system and OS and even if you didn't know the system or language all that well to begin with, you would still manage to become fluent and productive in it in reasonably short time. It takes experience and some understandings of the fundamentals of computers, software and networks and some curiosity and will to find things out and better yourself but if you want to be a programmer and even work as one, then this is what you should aim for... be "fluent" enough on (almost) all OSI layers so you can figure things out and understand what is really going on and whatever very-specialized knowledge will be required at a certain point in time, you will be able to figure it out and pick it up along the way because you will have the broader overview and understanding to connect things. Level 5 sounds close but still too limited still.