Hello,
I have been working with Joomla since version 1.5 came out, so I have a lot of experience with this particular CMS.
I visited your websites, and it seems most of your problems are coming from a few plugins, and this Joomla file: libraries/src/Helper/ModuleHelper.php. What puzzles me is that returning to a previous version of PHP didn't fix the problem.
I can start working immediately and fix these issues. Send me a quick message, and we can figure out if we are a good fit to work together!
Pedro Carbonell