Hey everyone! Glad to hear you like this update.
Regarding Advanced levels, it depends on a language, but basically required number of Known words to reach the Advanced 3 level is the same as needed to switch from Advanced 1 to Advanced 2.
For example in English: English Known Words for Advanced 1 = 20,750
English Known Words for Advanced 2 = 30,250
Gap between the two: 9,500 words.
Therefore Advanced 3 should require 30,250 + 9,500 = 39,750 Known Words.
Advanced 4 should require 39,750 + 9,500 = 49,250 Known Words.
And so on.