It seems to me that you have a pretty bad case of corrupted files. I hadn't actually seen something like that actually happen, but I figured it was possible.
If you want to correct this, I'd say you should delete all data for SmileBASIC (including the app itself) and redownload everything. If you want to keep some of your files, make sure to back them up to the cloud (upload, but don't publish).
Considering that the text string "PCBN0001" is there, it's possible that your GRP file somehow had it's file type flag corrupted to be TXT.
One possible cause for this is that you might have improperly imported the file using external tools.
(PCBN0001 is SmileBASIC's magic number)