According to a recent post:
.. there currently is no specific temporary rate limit for cPanel at the moment.
All other regular rate limits are there to prevent an overload on the Let's Encrypt systems. I'm sure you're not the only cPanel user out there having issues. Relaxing the regular rate limits could cause such a load spike with all kinds of repercussions for everyone.
Could you perhaps elaborate on why your sites are down? Have the end leaf certificates expired and do you require a renewal? Or is this a certificate chain issue?
Also, perhaps https://forums.cpanel.net/threads/cpanel-33077-letsencrypt-transition-to-isrgs-root-important.673981/ has information which could be helpful.