I'm back. The Blocksy team had a look at the log you provided me and gave me a test version of their Blocksy Companion plugin. I have updated my site with it. Here is what they had to say:
"After taking a closer look, this does seem like something that could be caused by us -- but only in the context of executing commands via WP CLI.
Our Companion plugin does implement some CLI commands for starter site install automation and it seems like it affected the execution of the "wp plugin list" command.
To confirm this, I can give you a build of our companion plugin that doesn't have the CLI component in place and we can validate if that's the root cause of the issue. We will probably need to involve the tech support of Ezoic...
I just tested the CLI on my end and there are no issues at all."
Can you please ask the hosting team to once again run the commands they did previously and email me the results?
Hopefully the errors are gone and themes and plugins can be listed properly. If that fixes everything else too with the odd WPML behaviour, etc., then even better!
Thank you again!