The common names on iNat should be those names that are actually in use outside of iNat. Not to be created for purposes of iNat identification. And I don’t think each subspecies has a common name–just the two subspecies groups. But iNat doesn’t offer a “subspecies group” taxon that could be used in this situation where subspecies are grouped into two groups.
I don’t think that folks who know birds are having a problem providing identifications due to lack of vernacular names in common usage for these subspecies. It looks like all your observations are being confirmed by at least one person except for the one’s with only sound recordings. I’ve noticed that people seem less inclined to identify sound observations–perhaps because it’s more trouble to listen than to see or fewer people are familiar with the sounds. I suspect the ID confirmation “problem” has a different cause than availability of common names for the two subspecies groups (or individual subspecies). I noticed that you’re observing within a contact zone with potential for hybridization. Can subspecies ID be confirmed without a doubt based on photo or song in this contact zone?
I’m not sure what you mean by “adding the scientific name to the common name”. Taxa are based on scientific names, to which common names can then be applied. Are you asking that the same common name be applied to each of the subspecies within the two subspecies groups? And then that the subspecies scientific names be included as part of those common names?