I may be mis-reading this post but it seems like you have written an Excel macro to create a .dsx file for your table definitions. You are then asking why these .dsx s do not import into DataStage. If this is correct then the answer is easy; Your reverse engineering (hack) of the DataStage export/import functionality is in error. Fix it. Does it really need to be said that the Excel macro must recreate exactly the format and layout of a .dsx?
My apologies if I have read this post wrong.
No, I don't think you're reading it wrong. It's obvious their assertion that they were able to create an appropriate .dsx file is incorrect. Compare your file to a 'real' file - what's missing / wrong?
-craig
"You can never have too many knives" -- Logan Nine Fingers