So, just to be clear, you tried something like:
tPath = baSysFolder( "personal" )
tPath = baUnixName(tPath)
fi = baGetFilename( "open", tPath, EMPTY, ".txt", 0, "Select a file...", 0, -1, 0 )
Or perhaps:
OK = baReturnUnixNames(TRUE)
fi = baGetFilename( "open", baSysFolder( "personal" ), EMPTY, ".txt", 0, "Select a file...", 0, -1, 0 )