Issue 1: When installed as a subdomain multisite with a subdomain, the sub of subdomain is NOT supported by SSL.
The following image shows that this can work, but I couldn't get the Let's encrypt SSL with wildcard DNS based sub-sub-domains to work.

That is, site1.msite.cloudron.club won't have SSL.
msite.cloudron.com > wildcard SSL will work
subdomain.msite.cloudron.com > wildcard SSL doesn't work.

Or is there something I am missing?

I quickly pivoted to try directory based wordpress multisite and used the following command in the terminal

/app/pkg/wp-convert-multisite --subdirectories

as per instructions from this documentation page as follows:

Open a Web Terminal. To use subdomains in multisite mode:

/app/pkg/wp-convert-multisite --subdomains

You can pass --subdirectories to install in subdirectory mode.

However, I got the following error - Issue 2:

/app/pkg/wp-convert-multisite: line 35: $2: unbound variable

And no changes were made to the .htaccess file.

I would appreciate if this can be looked into please. Thank you!