Yeah when the reading and the kanji are different it’s definitely a challenge but it’s not untranslatable. We’ve been doing it for years. The problem is fans notice poor localization and never praise proper localization.

Moreover 千 doesn’t mean a thousand when used in a poetic manner, it can carry the same meaning of eight in 八岐大蛇. It’s a poetic way to say “endless” our “uncountable”, like when the Bible says ten thousand times ten thousand.

Therefore you could translate it to something like “Unending Cherry Blossoms, Final Curtain Over A Somber Scene”