St Johns is right next to Charlotte county and Charlotte is where the Maine Penobscot loyalists settled in 1783.
There was a Noah Fernald born 23 Sep 1759 son of Benjamin and Fernald Sarah Fernald. He is listed in world connect as having died before 1798 as he was not listed in his father's will. Noah is also 1st cousins with Benjamin Fernald and Sarah Beaver, whose daughter Mehitable Eleanor Fernald Spinney settled in NB in 1815.
I am only guessing. But if you research these clues, I suspect the line of Alexander may be connected to Renald something like this...
8. Alexander B. Fernald and Sarah E. Dehart 7. George W. Fernald and Emily Brown 6. Mark Fernald and Ann Y McNeill 5. Noah Fernald and Rachel? 4. Benjamin Fernald and Sarah Fernald 3. Benjamin Fernald and Catherine AND (brother) Ebenezer Fernald and Patience Mendum 2. William Fernald and Elizabeth Langdon 1. Renald Fernald and Joanna Warburton