If you bought the SH5 game you have a license to all the files contained in it. As long as I don't modify any dlls or exe there is no legal ground for anyone to stand on. Furthermore since the app asks you to point it to your granny2.dll file it is using your licensed copy of it.
Using tools from Microsoft I inspect the granny2.dll to figure out function calls. Just now I found in the exports section all the defined vertex formats that granny uses. From that information (and some trial and error) I make my code.
Just read in all the binormal and tangent information with each vertex
There is not a granny vertex format defined that reads the second UV coordinates. Thus there is some function in that dll that does this. Now to find it.