Is there any Errata on why the Carcharodons Chapter specific skill is "High Gothic"? Don't all Space Marines know High Gothic by default? Was this suppose to mean Carcharodons only speak High Gothic or is this suppose to be an Advance Skill High Gothic (+10)? The second option would make more since as they are suppose to speak and older dialect of High Gothic based on the lore in Honour the Chapter.

Basic Linguistics would probably be enough to say simple words like "Go", "Stop", "Come here" etc.

Trained (which is most marine standards) would be to elaborate on it with "What is over there?", "Where is the guard outpost?" or my personal favourite, "Did you see a rampaging Hive Tyrant run through here with an injured space marine in its mouth and one on its back stabbing away with the blunt end of a bolter?" They would struggle though if someone responded using obscure terms or a version of High Gothic only used in a small hive somewhere.

So to answer your question they would be a bit more advanced at it and have the ability to detect subtle nuances and slight dialect variations as well as grammatical errors that others may have missed so our marines might get away with basic stuff with a few mistakes in their wording but enough to pass mustard. It would also be used to probably identify uncommon or lesser used terms of the language. So it would be the Carcharodon who recognises and corrects the use of Romanes Eunt Domus with their advanced skill in High Gothic.

Thanks for the feedback. So from what I gather on your comment then you mean to say that you would place Carcharodons with a +10 skill training in High Gothic?

Pretty much