Is there any easy method for opening the text file if you are running your app from the same directory? I can't seem to find anything easy. 
I am asking because you can do that with most of the things in kivy (for image: "name.png", for .kv: load_kv("name.kv") and so on) and I don't understand why it wouldn't be similar with finding a text document.
Just open('filename') - the path is relative, so if its in the same directory you don't have to do anything special.
If this appears not to work, perhaps it isn't your syntax that is the issue.
Open (read, write) a file in same directory as main app - python/kivy