I just noticed that if the text blitter does not contain any text at frame start-up you cannot load text from an external file. And even if it does contain text loading an external file will only return a string which equals the length of the string text blitter had at start-up. "Monkey" will only return the first six characters from a file, "Fire" returns four and so on.
I also seem to have problem overwriting an already existing file. Workaround is using the file object to check if it exists and if so, delete, and then save the text to an external file.
So then am I doing something wrong or is this a bug?