Hi there! 
The guide that @luisherranz and @David shared during their workshop “How to Create a React Theme in 30 Minutes” at WordCamp Sevilla 2019 is now available in English.
However, please note that some explanations and context they gave during the workshop might be missing. Feel free to ask if you have questions. 
The full workshop (in Spanish) can also be watched on WordPress TV and YouTube.
