I've never heard the term applied to a keris before, but there are a million or more keris terms out there I've never heard of.
Yes Alan, undoubtable so. If you google "anak alang guling" you will discover that it is terminology that is being used today, but i don't understand the reasoning for it since all the supposed example of it just look like keris anak alang to me. The "guling" part of the name seems superfluous.