Many thanks for your quick reply. (Yes, it would be ideal if the feedback button could be displayed anywhere in the course.) I will check out the examples on the link you provided and learn from those. As my coding skills improve, hopefully I will be able to turn this Wordpress plug-in into an Adapt Extension plug-in someday! ;) Thanks also for the helpful insight re: collecting the users' comments.
I saw that Adapt Plug-ins currently exist for feedback for question components, but I couldn't find one for collecting general feedback/comments from users. I would be very interested to hear if anyone else has any insight on this. (I suppose it would also be possible to collect user feedback via an LMS (using SCORM or Tin Can API/xAPI), if the users sign in as a "guest" first...)
Thanks again for your help, Fabio!