Can you give me (super) admin and (s)ftp access so I can take a look?
You can use the 'Confidential information' button in the forum editor to hide sensitive information.

I can't/won't use a Joomla file browser to change files. If I change something that breaks the admin, I have no way to fix it.
So if you can provide direct (s)ftp access, I am happy to look into this further.

Please try the latest development version from:
regularlabs.com/development-releases

But I must say: You have an enormous amount of data on a single page, because of the many nested tabs.
This makes the page load and react pretty slowly.
I recommend thinking about re-organizing the pages.