I’m new here and reading through stuff to get a feel for things so maybe I should shut up and leave this be.
Oh well. This thread follows similar debates that have gone on since people developed language and started giving things names. It is necessary to have some guidelines about this in a place like iNaturalist but language is language; it evolves according to its own rules.
Scientific names became standardized when Latin was still the international language of science in a bunch of countries. That’s why many of the names are Latin and the rest are latinized. The reason that it works better than common names for communicating is not that it is latinized, it is that there is an internal logic to the naming system that helps organize species in groups. Species are unique; they belong to genera with other species that share characteristics. Common names don’t work that way at all. A lake trout in Scotland is a Salmo trutta that lives in a lake. In Canada it is a Salvelinus namaycush, a member of a genus sometimes referred to as chars or charrs and has therefore appeared in scientific publications as lake trout, lake char and lake charr.
Before Europeans started wandering around Turtle Island giving things European names (like calling Turtle Island North America) Salvelinus namaycush was just namaycush (if you were a member of some Cree cultures) or namegos (if you were a speaker of Anishnaabemowin like the Ojibwe).
The complexities and occasional absurdities of this business are demonstrated by the iNaturalist entry for Salvelinus namaycush, which notes lake trout as a common name, but not lake char or lake charr. It also includes two very local terms for the species that are rarely, if ever, used in publications but excludes others. It does not mention that in the Laurentian Great Lakes the nominate subspecies is widely referred to as lean lake trout or just leans, while the Siscowet (an Indigenous name) subspecies is often called fat lake trout or just fats. The entry for Siscowet says that the English common name is Siscowet lake trout. If that is so, somebody needs to tell the people who fish for them, sell them or study them because they are just Siscowet to everybody I know, and have been since long before Europeans showed up on Lake Superior. Well, that or fats.
This is not a complaint. I just want to make the point that nomenclature is a dicey thing when you start slicing things fine; getting the etymology and usage right for every name of every species is not going to happen. Anyway, iNaturalist is not going to settle any of these arguments. Names should allow clear communication. The best we can manage is reasonable, clear rules about what names get used, what gets referenced, and where the lines get drawn. My vote comes down in favour of not allowing a common name that isn’t actually common somewhere substantially more geographically extensive than your friends’ basement or found in a publication (popular or technical) that makes a persuasive case for it. I’m happy to leave the final decisions to Curators.
If there is a critical mass of folks here with ethno-cultural-linguistic competence who want to start a working group to beef up the taxonomy functionality of the software, go for it, I say, as long it doesn’t turn into a postmodern deconstruction of taxonomy as a manifestation of hierarchy or some other questionable use of bandwidth. My own priorities would run toward putting in an effort to include indigenous names for species (especially when they appear in the scientific name) ahead of some other projects. In cases where there is an indigenous name but no English (or Spanish, or French, or Mandarin) common name, the indigenous name should be inserted as the common name. Cataloguing them would actually serve a purpose, although I’ll leave it up to others whether it’s a purpose suitable for iNaturalist.