Hi,
I did a quick(!) verification if the UMC-module would at least leave the system in a halfway useable state. This was the case but as expected and announced by a warning before saving the new CA there are additional steps to be done.
The first error in your case looks like one component did not know about the new CA. Under normal circumstances the steps from Renewing the SSL certificates especiallyupdate-ca-certificates and a restart of the services should be enough.
Your last screenshot is missing the explanation for the found problems but I would also expect that they can be solved by walking through the the mentioned article.