If you are encountering the 16k character limit error when creating your template, the reason is likely due to the source where you are copying your content from.
Our builder is full html and sometimes when you copy text from another program it also picks up unwanted html and formatting which causes this error.
The solution is when you copy and paste, paste as "plain text" which will remove all formatting.
Or you can copy it a program like notepad, and then paste it back into the template editor.