@sub2010
I use the same config. domain.tld and matrix.domain.tld. I'm not sure about your srv record, I dont use one.

For my certificate I use 1 certificate. In acme you can specify multiple domains for one certificate. Mine includes. *.domain.tld and domain.tld

Get a cert like that, put it on your haproxy frontend and also put it on your matrix host and point your homeserver.yaml to it and restart matrix. The error is still saying your cert is expired, so I am assuming the cert you have on your matrix host that your homeserver.yaml is pointing to is expired.