I'm not able to offer any help identifying the wives of the John Colwell Browns you listed, but I'd be very interested to learn what you know about them.
A John Colwell Brown appears on a 1764 tax list from Lunenburg Co., VA. He was the son of Valentine Brown and wife Ann. On a 1748 tax list from that same county, Valentine Brown is shown living very near a John Colwell, and I can't help but wonder if Valentine's wife Ann was his daughter.
The 1753 Lunenburg will of John Brown (wife Joan) identifies Valentine Brown as a son, and John Colwell Brown (listed as Caldwell) as a grandson.
For a number of years myself and another researcher have been trying to sort out the Brown family groups found in Amelia, Prince Edward and the northern reaches of Old Lunenburg counties, circa 1735-1775. Some we know to be from my DNA Group No. 69; others appear to be from DNA Group No. 10; and still others we are uncertain about. We have long wondered how John Brown, son Valentine and grandson John Colwell Brown fit into the overall picture.
Do you have any information showing where your John Colwell Brown Sr. hailed from? The Colwell Brown listed on the 1809 marriage bond was undoubtedly born before 1788, making him of the right age range to be a son or grandson of the John Colwell Brown of Lunenburg Co., VA.