Howard's use of K suggests a Q-Celtic, which would fit in with his own study of Goidelic languages. Perhaps the original Proto-Celtic would be more suitable?
What part of this statement from REH (quoted just a few posts back) are you misunderstanding?
"So while Bran Mac Morn is Gaelic for "The Raven, Son of Morn", Bran Mak Morn has no Gaelic significance, but has a meaning of its own, purely Pictish and ancient, with roots in the dim mazes of antiquity; the similarity in sound to the Gaelic term is purely coincidence!"
The term "mak" (in his Pictish context), according to REH, has no Gaelic/Goidelic/Celtic/Indo-European significance.
HTS, I know you fancy yourself some sort of linguist, but when discussing Howard's sub-creations, a minimum of familiarity with his concepts is required. Robert E. Howard set the rules for this game. There are threads specifically about the historical (ie, "Celtic") Picts on this board. There is also a "Celts" thread. If you can't accept Robert E. Howard's concepts, feel free to pontificate where such is perfectly acceptable.