I think this is a great idea! You’re very right about dialects I’m from the south of the UK and spoken English from say a Glaswegian can be hard to understand at best by most Brits! However written word and grammar is largely similar throughout the English speaking world, with the ability to hear a verbal version of written text a non native speaker could learn a lot as one of the most difficult things with foreign languages is scentence structure and gendered words. I don’t expect anyone to get to grips with their, there and they’re as the majority of the UK uses them wrong anyway .

Good idea buddy