I don't know whether the Pearson team looks at reports for their own sentences at all, nor how many people they have and how much time they have for reviewing sentences.
On the public course, a week is much too short to expect a response, I'm afraid, given the number of volunteer contributors and the free time they have each week versus the number of sentences in the course.
What is the difference between dies and mein? We wouldn't say meiner Tisch, right?
Soooo, I get the feeling that dies behaves like an adjective. Is it considered one?
I'd call it a "demonstrative determiner".
And it doesn't behave quite like an adjective -- the endings are like the definite article, e.g. -s in masculine/neuter genitive, while strong adjectives have -n: der Preis guten Weines versus der Preis dieses Weines and der Preis des Weines "The price of good wine / of this wine / of the wine".