Unfortunately, that is out of our hands. We do not have any control over it and the Siteground should fix the issue. The problem is that the tool does not change the actual URL of the website in the database and that is why the standard home_url function of the WordPress does not work correctly and our builder is heavily using that to determine the base URL of the assets.
We had been in contact with them and they provided this temporary workaround:
https://theme.co/apex/forum/t/troubleshooting-builder-preview-warnings/14404 (Read the last part related to the Siteground)
Even after that, we have reported that now people are experiencing the Too Many Redirects problem.
Regarding the other question, we can not give the official recommendation for 3rd party plugins but this article might be of a help for your research:
Thank you for your understanding.