Need help with Multilingualizer

Hello, everyone!

As the Multilingualizer seems to be the most affordable way to do this, I want to give it a try to add another language to our site

Unfortunately it is not possible to test this first on the domain
To avoid the problem of the tool firing in the editor (where you should see all languages to edit), they decided to disable the code generally if is detected.

I really want to test this first before going live, there might occur critical details with margins or layout within different breakpoints when the language is switched.

They suggest to set up another custom domain for testing purposes, but I had the feeling that this would be problematic with the google indexing…

Am I right with this?
Any other ideas?
Has someone lately worked with the Multilingualizer?
If so, how did you deal with this?

Any help would be much appreciated, thanks!

That has been solved:

Sorry, but no, this has not been solved. The “upgrade” mentioned in your first link leads to the problem I described above, and your second link files a different issue.