>>51342416As annoying as it is, The Pokémon Company (TPC) made the choice to localize her name as Green in the Let’s Go games, so she is officially Green in english speaking countries. In a way, this is no different than having local Pokémon names.
That said, their choice was bad. In Let’s Go, Oak’s grandson can be found at Viridian gym. Viridian is the color green. “Green” (Blue) is found at Cerulean city. Cerulean is the color blue. TPC should have corrected the names in the Let’s Go games.