Also https://www.openstreetmap.org/#map=8/43.622/-78.852 shows "Lake Ontario". But it does carry the tag "official_name:en-US": "Lake America", so search will find Lake America and a mapping app could decide to show the official name

Though generally official names are the names nobody uses. For example the country labeled "France" also has the attribute "official_name:en": "French Republic"