I'd just like to confirm that --dns then becomes redundant when issuing subsequent certificates?
No. what if you want to use another dns api?
If I want to change DNS provider, I must then edit
~/.acme.sh/account.confdirectly.
Never do that. it's not recommended to edit it manually. The variable's names are not promised to be constant.
Is there a way to test this functionality without waiting 60 days?
No, this is the CA's behavior: how or when the certificate expiring notice will be sent.
Don't rely on the CA's notifications. This is not a part of the ACME RFC 8555. A CA may choose never to notify you.
If you want a reliably notification, please use our --set-notify feature: notify · acmesh-official/acme.sh Wiki · GitHub
where the email details are stored from the installation and how it's used. For example, if I install acme.sh as follows:
The should be saved in $LE_CONFIG_HOME/account.conf.