I disagree with the interpretation of the curator guideline: Please don’t add information to a name in addition to the name itself, e.g. “grumblefoots (this genus is monotypic, just ID to species!).”
I consider it quite proper to add geographical disambiguation to a name, which is very different from a comment about the name or species. For instance the common name “peacock flounder” is applied to a pair of similar fish, one in the Atlantic and one in the Pacific. What we eventually did with this case was to leave that common name on both species, but to make the primary common names “Atlantic Peacock Flounder” and “Pacific Peacock Flounder”. These species have been well known for decades. In the case of recent splits, it is particularly valuable to do this. The guideline seems to be saying don’t name it “Peacock Flounder (the one with the eyes wide apart)”.
Along the same idea, you could leave the name “Common Flesh Fly” on Sarcophaga carnaria but make its primary common name something much more specific. Though here is where you risk running into the rule not to make up names. Is there a specific one that this species is also known by? I don’t know this group to know what would make sense, but something like “European Striped Flesh Fly”.
-Mark