That shouldn't be a problem, then. There's no need to prove existence via an external source, just your personal experience (source=survey or source=local_knowledge) is fine.

If the name tags is how they present it, I'd say that's fine. Adding name:en, like name:zh just makes it easier for data consumers. As for addr:unit, you'll still be discovering new tags or ways to tag things years later :-)

For food premises, you can often find additional information including addresses from the Food Hygiene Rating Service (FHRS), which is licensed under the OSM-friendly Open Government Licence. New premises can take a while to show up, but the FHODOT tool makes using the data easier:
https://gregrs.dev.openstreetmap.org/fhodot/?lat=51.54235&lon=-0.14233&zoom=17&layer=fhrs