If you make a backup of the save folder, you can put it back, But the favourites are stored in the user.upoi file in the save folder, copy it from the old save folder to the new one (Plus anything in Userdata\POI) to retain them.
But before that, change the baud rate in the system file you referred to and try it again, The reason why we say to delete the save folder all the time, is because it sometimes holds onto incorrect settings and leads us to believe something else is wrong.