Thanks for chiming in, all! I reamed the bowls gently, and sanded the very thin layer of remaining carbon smooth and even. Then I q-tip swabbed the inside of the bowls with 151 vodka, and put some baking soda in and rubbed it into the walls, like a rough paste. I was careful not to get any outside of the bowls as I do know that baking soda is abrasive. After a half-hour, I rinsed with warm water and scrubbed the insides with my finger. After drying with a paper towel, a few were already odorless, and the the other two required a repeat treatment...but as an end result with not much time taken, I can say it was quite successful! The bowls are almost totally odorless, even with a very thin layer of protective cake remaining.
I imagine a longer setting time could eradicate even the most ghoulish of ghosts! The vodka was probably not even necessary; water would probably do just fine. In that case, that would be a completely worry-free and easy home de-ghosting method. Next time I’ll try it with just water and baking soda, and then report back.