Cloudflare does say my "universal certificate" has Let's Encrypt as a certificate authority, yes.
I suppose that, because I'm using certs that Cloudflare gave me and Cloudflare is using Let's Encrypt, the evidence would indicate that the certificates I closed earlier likely have closed and revoked successfully and my server is now using the Cloudflare-provided Let's Encrypt certs instead.
Is there a way to verify that the certs that are showing online match my cert files?