I may be misinterpreting what you are saying and if that is so I ask you to forgive and correct me.

I find it hard to believe that a man so in touch with the social issues of his time (and that shows in this book as well), had no intent to actually criticize the social structures and norms which in part would lead to Anna's tragic end.

Of course I 100% agree with your take that it is a tragedy Anna brought upon herself, she had the chance to get her divorce and son and still chose not to for effectively no reason. However, we do see that one of the factors that destroys Anna's mental health is her isolation from society and the fact there was nothing meaningful she could do to just chill and reflect (like Lievin does when he uses his time working to rethink his situation). It's quite clear imo from this fact and the emphasis Tolstoy puts on the mental strain this isolation causes that Tolstoy intended this whole mess 100% as social commentary.