After completing the 7.1 Archon Quests and starting the Secret Tsarist Assignment, you can meet the Tsaritsa in several places near Zapolyarny Palace. You can complete all interactions in one day, just teleport to another location and come back. There are 8 interactions in total.
1 and 2
Anastasya can be found in front of the Zapolyarny Palace entrance with 2 different interactions.
(The Tsaritsa seems to be looking in the direction of Celestia...)
Anastasya: Out there, somewhere in the distance, is the star you hail from, no? Could you point it out to me?
Anastasya: ...On second thought, let us save that moment until we can gaze upon the true starry sky.
3
The Tsaritsa can be found to the right of the Zapolyarny Palace during the day.
Anastasya: At last, it has begun...
Anastasya: ...But it is not over yet.
4
At night time, the Tsaritsa can be found at the same place with a different interaction.
Paimon: ...Why is it so cold all of a sudden?
Anastasya: I would advise keeping your distance at this time.
Paimon: Ah, the Tsaritsa...
5 and 6
Anastasya can be found inside Zapolyarny Palace, in the room to the right of the entrance. There are 2 different interactions.
Anastasya: What do you think?
Paimon: It's really pretty!
Anastasya: Hm, pity it's not real. We cannot grow plants in the palace.
Anastasya: Some flowers bloom under the presence of frost, and others bloom when it melts.
Anastasya: The question is... which one do people favor more?
7
There's an interaction in the left room as well
Anastasya: Yes?.
Anastasya: I still have reports to review. You can wait for me in the sitting room.
8
Another interaction is in the same room.
Anastasya: Is that all?
Unknown Minister: ...Your Majesty, we're all willing to make a concession.
