I'm going to assume that you're arguing in good faith and aren't just a troll.

I myself am very anti-war, but I tend to take a more practical standpoint, because in order to avoid war, both sides must work at peace, not just one.

There's a few problems with your line of thinking.

For one, you suggest that Russia formally agreeing to tolerate Ukrainian culture would be enough, but suposing Ukraine did back down on that condition, how could they possibly trust Russia to stick to their word once any bargaining power they had is gone, especially since Russia has previously recognised Ukraine as a sovereign nation and had no problem ignoring their own word on that.

That brings me to problem two, or modern day notion of nations is relatively recent, but it does seem to work. Before the world wars, there was always borders changing and this was seen as normal. But since at least world war II this has changed, nowadays nations choose to recognise other nations right to exist with a given set of borders, this is a fragile system and if we simply allow countries to arbitrarily go against it without any repercussions, then why would any other country abide by it?

Also if Russia and Ukraine could agree to have Ukraine become part of Russia, I, as someone from neither country, would have nothing particularly against it, as long as it was entirely peaceful diplomacy, Russia removed that option the moment they started gathering troops near the border, because at minimum, that's a threat.

I am no expert on the history involved here by any means, so if I have made any mistake, feel free to correct me, I'm simply thinking through the logic.