Can I use a China-version robot's app in English?
Partly
It depends on the brand and app. One China X50 Ultra owner saw the official app in English because it follows the phone language; a China Ecovacs owner got Chinese everywhere. VacDeck gives the robot a complete English interface either way.
Today the robot's spoken prompts stay Chinese; translated voice packs are coming soon to VacDeck. Sources: Reddit, X50 language thread; Reddit, Singapore thread.