If there is a near concensus, that is good enough.
If the era is named in some other language only, we’ll take the nearest translation.
If a very similar term is used, that's good enough. Ie Internet age = Internet era = internet period. If you have edge cases, you are welcome to ask for clarification before betting on it.
Resolves to the judgement of whoever’s in charge of this market in 2100.
@Stralor but if there's overlap then it can have multiple resolutions. 100 years ago was the Roaring 20s (in the US at least), it was also the interwar period, it was also the "age of extremes" if you care about Eric Hobsbawm, it was also the industrial era, it was also the modern ages (or "contemporary" age, if you ask the French), it was also AD (anno domini) and so on.