Sorry for the late reply. He's releasing hints to the new season on Instagram from quite some time. This one is a promotional image from the first season, but there were others with a Latin motto and one with a rhyme and a possible date. You can find them listed on the Season Two's note section.
Season 2 is expected to go in production in September. If we're lucky, we'll get some more info and details in the next few months.
Based on what was said between Lorna and the Countess, Colonade seems to be a figure of the network of spies in contact with the Americans. Possibly one of the heads behind the fight against the Crown and the East India Company, since we found out that Carlsbad/Countess Musgrove was just a pawn. It's possible that James wants to meet this "Colonade" to enter into a new covenant concerning the Treaty of Nootka Sound, or at least look for alliance to establish his trades.
Very excited! With the cancellation / end of some of my favorite series, I am on the hunt for dark and exciting new show!