@arpeggidio
Sorry I forgot about you ....
I reread the last few posts but I think I understand .
I'm not sure sure appending text to the file when it is an internal extra should work.
Why ? Because android doesn't unzip the apk when it plays it. So it cannot write inside of it. Normally you should be able to read it
possible (untested solution) : copy the text from the apk to the userDirectory and applicationStorageDirectory then write to it.
note to self: check what is userdirectory and appplicationStorageDirectory/
Now it's compiling
and I'll tell you how to do it with a tested solution