I believe so. A check for the number of certificates issued per day / week is certainly doable. There are 2 aspects of it, which may complicate UI a bit:
- number of certificates with exactly the same set of domains, i.e., coming from (hopefully) the same certbot copy
- number of certificates per registered domain
The next update of KeyChest introduces notifications (new certificates) and a RESTful API. The first could be extended to cover LE rate limits, the latter could be used to hook KeyChest to Certbot to improve data for KeyChest notifications.
My feeling is that what you're after is to learn about config. errors and 1 or 2 days delay is not such a big issue. In that case just an extension of notifications should work reasonably nicely.