So I found a work around if anyone is interested. If you highlight something on the mobile app, then access the note on the web, you can copy paste highlighted text elsewhere and then change the text, but keep the highlighting.
Example:
Previously highlighted text
copy paste
Previously highlighted text
Previously highlighted text
type new words
Previously highlighted text
New wordsPreviously highlighted text
clean up
Previously highlighted text
New words
Ta-da! A dumb work around to perform a function that is mysteriously difficult to implement. But there it is!