No, it has
no connection to Bonnie Cashin. That's just another seller who knowingly or otherwise misleads bidders into thinking the bag is more rare than it really is. Bonnie Cashin left
Coach somewhere around 1974 and almost NO bags with serial numbers are genuine Cashin bags, especially not bags with the modern-style numbers that include a letter of the alphabet. Ninety percent of the listed "Cashin" bags are nothing of the sort. Yours is from 1996.
ETA - It's from a line that began sometime in the late 1980s and was just called the Lightweights because they used thinner leathers, lighter hardware and zippers, and just about anything else that could shave a few ounces of weight off the bag, because it was right around that time that the problems a lot of women were having with their neck, shoulder and back muscles and nerves because of overloaded purses was coming to light. The name was changed to Soho Lightweights in the early 90s and it eventually morphed into the current Soho line. The horseshoe-shaped buckle usually indicates a Lightweight or Soho although not all of them have buckles.