1. The Index in 1616 was the vehicle Pope Paul V used to make the heresy known to all.
If you say that, then why not: the 1835 Index was the vehicle the Pope used to make the non-heresy known to all?
Each of the points I listed above you
must hold, but there are good reasons for the opposite.
1. The Congregation of the Index seems to me a disciplinary body, and not a competent body for doctrinal statements (which would be the Holy Office)
2. Even if the Congregation were a doctrinal body, the 1616 statement looks disciplinary. And furthermore, it looks specific to Galileo's books and a couple others. The resulting index required Galileo's books to be published with corrections. All he had to do was state things as a hypothesis rather than certain. If this was truly doctrinal, then the Church (in 1616!) allowed people to state heresy as a hypthesis, as long as they didn't assert the heresy was certainly true. That's absurd. The obvious conclusion is that it wasn't a doctrinal decision at all, but a prudential one.
3. Even if it were in force, it would, strictly speaking, only require the corrections for Galileo. Since Galileo's books went off the Index entirely, it would seem it was, in fact, reversed.
4. Even IF it were granted that the Index can issue doctrine, and even IF the 1616 statement was in fact doctrinal, and even IF it applies to more than Galileo and his books, and even IF it is still in force, the traditional way of interpreting penalties is strict interpretation. Since the 1616 statement refers to the "doctrine" (singular, not plural) including BOTH the sun moves and the earth does not, a cosmology which holds the earth moves doesn't fall under that penalty. (That's in addition to the "not violent" part you mentioned regarding "as affirmed today").
5. The 1820 statement explicitly says there is no obstacle for Catholics to hold "the earth’s movement in the manner in which it is affirmed today". Since your entire argument is "authority", you have to deal with this "authority". You're basically arguing the Church failed in its teaching since at least 1820, that is, the gates of Hell prevailed against the see of Peter. That seems a difficult position to take for a Catholic.