>All these regional problems are mainly due to the language. If Ukraine allowed Russian as it's second official (or at least regional) language, Donbas would return back in a blink. And Crimea might follow.
What? History goes back farther than the 20th century.
So Moscow should be handed back to Ukraine, the late seat of the Kievan Rus' [1]? Or perhaps the whole thing goes to Mongolia.
Originalist interpretations of border disputes are infinitely flexible, and justification for constant warfare.
And much farther than 18th century. Crimea has a long and rich history, Russian power is relatively young and not justified in the modern world. Wasn't one of the ideas of Helsinki's agreements to agree on non pursuing historical territorial disputes?