The fact that she lives in a monarchy that is negatively disposed towards socialists does not in any way negate the fact that Tanya first positions herself as a defender of the liberal world from the commies (which in itself is ironic), and then openly lists herself as the spiritual heir of the dictators and emperors who fought with Russia.
Two of the three examples you gave took place in the Middle Ages and during strong political-economic crises in Russia and Kievan Rus. First, rough feudal fragmentation (not to mention the fact that the Mongols as a whole had completely unique military techniques and tactics for the region and era, which allowed them to conquer not only Russia), when everyone was for himself, and then a time of troubles during the fall of the Rurik dynasty and disputes around Godunov’s problems. It would be very speculative to compare them with Napoleon or Hitler, And in both cases, the Russians ultimately won thanks to the restoration of strength and the emergence of conflicts within their opponents (the victory and expulsion of the Poles is still celebrated as a day of national unity in Russia). I don’t know what Baltic wars you are talking about, however. As I said before, winning or losing a war comes down to a combination of many factors, not just the weather.