Hey, thanks for telling me about it.

To clarify - do you mean that even if the address on the sign is only given in Hindi, I should use addr:full=* rather than addr:full:hi=* for the Hindi text?

The only place on the wiki where I found something regarding this is https://wiki.openstreetmap.org/wiki/Multilingual_names#When_name_is_only_in_one_language ...but it's not clear to me what it is suggesting.