Your link on RAW files is exactly that... a link on how to read .raw files.   That is not the issue here.   In the process of removing the card from the computer after setting it up (likely without safely ejecting it) the card got corrupted.  The information that defined the card as a FAT format got clobbered, so the card things it is a RAW format.    This can happen, w/o altering any of the other data on the card.

The GS2 requires the data on a card to be written with the FAT file structure, but as the GS2 is not actually a normal computer, it's OS is going to read that structure, even if certain bits on the header of the card are not correct.   That's why the GS2 is still able to read the card.

Were I to try and solve this, I would try my array of disk image copying software from companies like Paragon.  Don't remember what else I have.   I would copy the card image, to make sure I have a copy of the raw data.    Then, I would do as bwire suggests... I would try to do a quick format in FAT mode (make sure you use FAT).   That will make the card appear empty.  But then I would try to use tools to recover data files from a formatted disk and see what happens.    Personally, I don't know how to flip the bits that make the card think it is RAW and put it back as FAT, and there may be other key bits that need flipped as well.

So... I don't think I have an answer as to how to recover the data... but I hope you might now understand what has happened.

BTW:  Have you called Stellar Support?   If the GS2 can read the card, they might have an internal utility for a GS2 simulator that could extract and copy the data.