The Nook Simple Touch is indeed "simple" and does not provide utilities to keep track of books read.
So, I use calibre and the calibre catalog to keep track of books I've finished:
1. Create a "Read" custom column in calibre.
2.
Remember to update the column after you have completed a book. This is manual, not automatic.
3. Create a calibre epub catalog with the option of showing a "prefix" (a tick-mark) for books that have been read.
When you export the catalog to your Kobo, you can easily see which books you've read.
This method does not address "percentage read", but it is bullet proof. The "Read" status is maintained in calibre even if your Kobo "goes nuts".
Marty