I wrote this in German:
Ich bin auf dieser Seite, nur meine Deutschkenntnisse zu verbessern, und nur mein Deutsch korrigiert zu werden.
In my mind, this was such a fine example of what may be called a multiple final clauses symmetry.
But a German speaker turned my original sentence into this one:
Ich bin nur hier auf dieser Seite um meine Deutschkenntnisse zu verbessern und damit mein Deutsch korrigiert wird.
When I read this sentence, I couldn't believe my eyes. My German interlocutor had just used two different types of final clauses (um ... zu and damit); and when I asked them why they had used this asymmetrical pattern of final clauses, I got no answer.
Why, then, was this asymmetrical pattern used instead of the perfectly grammatically symmetrical pattern that I had used in my original sentence?
Is there a grammatically objective reason for this?