I think we need to step back from specific peaks of the Annapurna range and look at the geography as a whole. The toponym, Annapurna, denotes a goddess of abundance who is often manifest as a overflowing jar (kalash or purnagata) , e.g., the Annapurna temple in Kathmandu.
Since the Annapurna range as a whole feeds the Kali-Gandak river (with an abundant flow of water) it is more likely that early nomenclature did not indicate specific peaks but simply the the massive overflowing abundance of the general area as the source of the river. The jar as goddess phenomenon is known inearly scypture and is associated not only with Annapurna, but also Naya Guhyeshvari, Puran Guhyesgvari and (according to the invocational inscription on the Annapurna temple) Yogambara/Jnanesvari at Mhepi-ajima.
Thus, it is my opinion the enumerations are a British "map-maker's" Nomenclature and not in any way traditional.
I hope this is useful,
John C. Huntington, Professor
Buddhist Art and Methodologies
Department of Art History
The Ohio state University