Computing a component's suitability also depends on dependability.
Likewise cycles/time. If the suggestion from Boeing is that frequency of unsuitable performance issues were not somehow addressed ad nauseum in the certification process, they are smoking other than Lithium Cobalt Oxide.
There is no reasonable explanation for FAA not to know about the replacement rate in service. None. If it was logged, they know. If not, some one or other or many are in very deep doo doo.