In my original review, I noted that I've had problems with the entire Duolingo page freezing and over halfway through a lesson, I end up having to dump everything and start over.
So, I deleted this and then the other Duolingo add-on and eventually I still had this same problem occur again. So I am deleting my comments.
Thank you for your response!
I have started taking screenshots and don't think this problem was due to the extension.
This week, I have found that Duolingo does have this feature. Last week it didn't!
I've also spoken to another user who is having freeze problems on a different platform, so that couldn't be this extension.
There was a problem with a "ghost" word tile being created that wasn't recognized by Duo, but was confusing for me. I wonder if it could have been a conflict with Duo's version.