The 'OG' online map platform, MapQuest, says it won't change the name of Lake Ontario
(www.businessinsider.com)
it’s in the data
Correct, because that's what official_name means. The US government, one of two countries encircling it, officially calls it "Lake America". That's why it's official_name:en-US specifically, not official_name=. The name= key, the "primary name of the feature in the real world", remains and will remain "Lake Ontario".
It’s not the name that is likely to show when viewing the map
I'll correct you and say that there's no "likely" about it: it's not the name that will be shown when viewing the map. That's the name= key, which is "Lake Ontario".