i don’t think i would add something like “Genus Egretta” as a common name for Egretta. i don’t think i would even add “Egretta” as a common name for Egretta, since i’ve ever heard anybody group them in that way except in a scientific name context.
i wouldn’t be opposed to “Zinnia” as a common name for Zinnia or “Crocus” as a common name for Crocus, since that’s the way laypeople refer to them, though. at the end of the day, i still wouldn’t try to force a common name for taxon that doesn’t have a common name.
in general, i don’t think this is thread is properly classified. it’s definitely not a bug. maybe a feature request. but i think your request might be better addressed as a post in this thread: https://forum.inaturalist.org/t/data-users-what-are-your-use-cases-and-requests-for-exporting-data/2972, not necessarily as a separate thread.
in the meantime, you can accomplish what you’re looking for by using a simple formula in a spreadsheet or database, i think. in Excel, you could do something like =IF(common_name=“”,rank&" " scientific_name,common_name),