you can add "Source" botton by adding 'Source' value to your "get_field" function inside "qa-wysiwyg-editor.php".
but you will need to see if user is a admin or not. on that subject read Plugin Development Documentetion.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.