This page covers every Obby app: Obby Thai, Obby French, Obby Russian, Obby English, Obby Spanish, Obby German, Obby Italian and Obby Hebrew.
Email luc@dvc-analytics.com — you will get an answer from the developer directly, usually within a couple of days.
Use the small report button inside the app (bottom-left corner during a quiz) — it opens an email with the word already filled in. That is the fastest way to get it fixed.
Only on your device. There is no account and no server. If you reinstall on the same phone, your phone's own backup (iCloud on iOS, Google backup on Android) restores it.
No. Every word and every audio clip ships inside the app. It works fully offline.
The apps collect no data at all — the one-page policy is at obbyschool.dvc-analytics.com/privacy.