I'm a little confused about what you're asking.
The ACME protocol uses TXT records, not CNAME. It is possible to CNAME the entry to some other domain, and the validation would then follow the CNAME like any other DNS record. But certbot doesn't support having the automatic TXT record created in a different domain than the one you're trying to validate by using a CNAME, so if that's what you're trying to do then you'll need to use a different client.
The other reason I'm confused is the snippet of the log you've posted looks like it's loading the Route 53 plugin and loading your credentials file fine. What problem are you having? I think you just didn't copy the entire log here. The easiest way to format it is to put three backticks on their own line before and after it:
```
content here
```