I know nothing about Recalbox, but for normal Dolphin I would suggest going to Config > Interface and setting the language to English.
If Recalbox uses a different version of Dolphin that doesn't have the usual Config window, you should ask the people who made that version of Dolphin,
If Recalbox uses a different version of Dolphin that doesn't have the usual Config window, you should ask the people who made that version of Dolphin,
