Yes. I can 100% confirm that you will NOT get anything else from the Oz Embassy. Immigration get confused because other embassies DO provide such a letter when a passport is renewed. ie US embassy and others.
You don't get any slip or a letter from the Australian embassy. Only the stamp. I just told immigration that my embassy does not issue any letters, showed them an email from the embassy that stated this.
Get a letter from your embassy that says you got a new passport. Or, if your embassy is like the Australian embassy that does not issue them, you need a slip or stamp in the passport that details that the passport was cancelled and replaced by xxxxx passport.
When you do eventually get to the point where you need a year extension of stay IN country....ie....the third year, you will need 800k in your bank for 2 months or more before your application for an extension of stay, 3 months after the extension is granted, and also for the rest of the year you need to keep minimum balance of 400k.......Another option is 65k a month transfers into your account, from abroad, permitted by some Immigration offices. Fun fun.
I see you don't have 400k in a bank account. Are you planning to arrange that? You should arrange it ASAP, and then you can stay for a year hassle free. All of this COVID business will go on for a long time yet. Get whatever extension you can in the mean time. Looks like a further 60 day is possible for people now.