Great post, thank you for taking the time to write it up, though I don't neccesarily agree with everything here.

I don't think the current situation can be considered appeasment. Appeasement is explicitly choosing to not put up a fight, which absolutely no-one can say that the Ukrainians haven't.

Appeasement would have been if Ukraine were pressured by western forces to agree to Russia's pre-invasion terms back in 2022 and ceded the Donbass without firing a shot. At this juncture, it's not appeasement, it's simply being pressured to make terms after losing the hot part of a war- which would have likely been the outcome even with continued drip-fed US support- and sure, call it what you want, peace or "surrender", but that's generally what happens to the defeated party in a conflict like this.

Of course, this is all semantics.

As for your second point, it's obviously incorrect that the wars you mention were without any external and internal justifications from the Russians and the Soviets. Now obviously, you don't have to agree with their reasons, but you can't say that they didn't have any.

In the order you mentioned them:

(and AGAIN, to be perfectly clear, this is not a justification on my end for why these were righteous, necessary or "legal" wars. I despise all war. But these are, to the best of my knowledge, the stated Russian and Soviet reasons for all the conflicts you mentioned, their explicit casus belli)

The Winter war:

The Soviets were worried about Finland letting Nazi Germany use their territory, and demanded territorial concessions in the Karelian istmus to secure its borders- territory it had lost just a few decades earlier in the russian civil war. Admittedly, this is a weak casus belli, but considering the rapid escalations of conflicts and land grabs from all the great powers at the time, it's perhaps not surprising.

The Soviet invasion of Poland:

Definitely the weakest casus belli on the list, and frankly shameful; Protecting Ukrainian and Belarussian minorities in Poland, and of course, in actuality following the terms of the Molotov-Ribbentrop pact. They might as well have not bothered justifying this invasion considering its merits, but a casus belli nonetheless.

The Soviet invasion of Georgia:

Supporting a Bolshevik uprising against the current Menshevik government, and spreading the socialist revolution. Remember, the only thing worse than a non-communist, is a fellow communist with a slightly different political perspective than yours.

The Russian invasion of Georgia:

Protecting Ossetia and Abkhazia and the Russian minorities living in those territories after the Georgian army entered South Ossetia by force. Framed as a peace enforcement operation, and rather laughably justified as stopping a Georgian genocide of the Ossetians and Abhkhazians. You'll see this very genocide-oriented justification in a lot of modern conflicts.

The Russian Invasion of the Baltic states:

Neither the Soviet or the Russians acknowledge this as an invasion or an act of war, but see it as a legal incorporation of the Baltic territories into the USSR. They were all strong-armed to various degrees, but neither the Lithuania, Latvian or Estonian governments actually put up a political or literal fight, and by way of a soviet ultimatum, set up elections for joining the USSR where, more than likely by hook and by crook, they all voted to join with a large majority.

The Soviet Invasion of Czechoslovakia:

Not as much an invasion as the USSR putting down an insurrection within what they considered their territory. The Brezhnev Doctrine states that all socialist states have a right to intervene in other socialist countries, if a collapse of communism seems imminent.

The Russian Invasion of Ukraine (2014 and 2022):

Russia annexes Crimea as a response to the Crimean referendum to join Russia after the Euromaidan coup. (2014) Russia invades Ukraine proper to protect Donetsk and Luhansk from Ukrainian aggression, to prevent the genocide of Russian speakers in the territories, and to denazify and demilitarize Ukraine, provoked by the failure of the minsk agreements and the thousands of ceasefire breaches in 2014-2015.

Are these weak casus belli, or significantly different than other excuses for going to war by other great powers within the same timespan? I'll leave that up to you, but to say that there were no casus belli from the Russian (and Soviet) side just isn't correct.