I watched the animated film when I was a kid, and my class was so into it that my teacher dedicated a week to teaching us about the Imperial family and the Bolshevik Revolution, which instilled in me a love of Russian history. Happily learning Russian now, largely thanks to that musical. It's a lot different from Japanese, and while it's not as close to English as Norwegian, it's close enough to make comparisons. They're both Indo-European, after all!
Anyway, back on topic, I'd love to see the stage adaptation despite the inaccuracies. I think the worst Anastasia film was that weird one with the talking instruments, and I know it can't be that bad! I listened to most of the soundtrack on YouTube and think it sounds pretty good, even without "In the Dark of the Night."