>>73093520That's an auto Japanese speech-to-English text translator that other hololive members have used in their streams before. I don't know if Okayu decided to use it because of Factorio or if it was just something she wanted to use regardless and Factorio happened to be the first stream she used it for.
Didn't Cover recently reveal that most of their viewing audience and consumer-base is the USA? I'm not surprised to see some of the JP holomembers doing things to appeal to overseas fans here and there, even in small ways like this.