The /keys/ and /csr/ directories are useless: they are not used for renewals.
That said, there is no easy way to migrate from another ACME client to Certbot: you'd have to manually write the renewal configuration file. Renewal also uses the original certificate. Basically, you'd have to recreate an existing certificate generated by Certbot. If any of the many details is incorrect, Certbot will malfunction.
You will definitely have to "try it".
Backup your current files and then make the test(s).
[beware of issuing more than 4 certs in a one week period - so limit your tests]
That said, I would adjust your "test" by removing the .csr file(s) and letting certbot create a new one.
I think that could work, although I'm not sure it will work. For example, I already told you the files in the /keys/ and /csr/ directory aren't used. Also, you'd need to fetch your staging cert with the exact correct options to e.g. prevent Certbot from generating a new private key with each renewal. It can be done, you just need to be very correct about everything.
It's probably way easier to just add another TLSA RR as @9peppe already suggested.