Write to wuyuking1012@gmail.com and you'll hear back. One person builds this app, so replies take a day or two rather than minutes.
Because labels rarely say where an ingredient came from. Glycerine, mono- and diglycerides and most emulsifiers can be made from plants or from animals, and the packet usually doesn't tell you which. When the source is unstated, the app says exactly that instead of guessing in either direction. Being told to look closer is the honest answer there.
Send the barcode or a photo of the ingredients list and say what you expected. If the underlying rule is wrong, fixing it corrects the answer for everyone who scans that product afterwards. These emails are worth more than they look.
No. It reports what is on the label and where that information comes from. Where certifying bodies classify an ingredient differently, it shows both positions instead of choosing between them. For a final answer, ask your local certifying body.
Barcode lookups come from Open Food Facts, a community database that doesn't have everything. When a product is missing, photograph the ingredients list instead. That path doesn't need the product to exist anywhere.
Settings, then Language. The app follows your phone by default, and switching takes effect immediately.
Settings, then Restore purchases. Purchases are tied to your Apple Account, so a new phone or a reinstall gets them back. If the button doesn't help, email the address above.
Clear the history from inside the app, or delete the app. Everything the app stores about you lives on your phone. There is no account anywhere and no copy on a server. See the privacy policy.
This is an ingredient information tool, not a religious ruling. For a final answer, check with your local certifying body.