How to fix the garbled text in my text editors?
I had the exact same issue with aGov distro. I had to swapped from ckeditor module to WYSIWYG module + ckeditor lib.

That fixed the issue with ckeditor. However, today I got the garbled text again while having batched processes running which preventing them to complete. Thinking back, I realised the problem started when I installed Devel themer &amp; simplehtmldom API (7.x-1.12). Uninstalling simplehtmldom fixed the issue for me.