Hi,
I think you might have some terms confused.
Self signed certificate: a certificate which you have created and also approved by yourself. No third-party entity has been involved. BBB doesn't work well (or at all) with these.
"normal" certificate: a certificate which has been approved by a third-party entity (Certificate Authority or CA).
This (normal certificate) is what seems to be going on in your log since you're using the so called acme challenges. For this there's a script which generates a certificate signing request (csr), asks acme (CA) to validate such csr and generates/downloads a valid certificate from the acme servers as well as installs it in your BBB server.
If you use a FQDN (Fully Qualified Domain Name) ending in .local acme will not accept it, since it knows most private networks (e.g. intranets) use this kind of ending.
You have to use a (really) FQDN to be able to install a certificate and BBB. You can see this in "Domain name does not end with a valid public suffix" (el nombre del dominio no termina con un sufijo publico valido).
Regards,
J.