Unfortunately we do not have a report that allows you to search for just certain register notes.
However there is a workaround to allow you to view this.
What you can do to is go to Reporting > Reports > Attendance > Student Attendance Reports (bulk). From here export this report a form group at a time. Pull up one of the PDF's with all the reports on and use CTRL & F on your keyboard to bring up a search bar. Type in the note you are looking for and it will highlight everywhere it says that phrase in the file. You can then see what date the note was added and who it was added to.