Notice that, for the case of English, most speakers are not native, by a huge margin! Native English speakers are a biased minority, and with a lot of variation within. Not sure that an "average native" accent is a useful concept at all. I, for one, tend to find most non-native English speakers vastly easier to understand than many native speakers.

The way someone speaks is very unique ... and it is actually very, very important how you speak to bring your point across. Or ... to convince people.

A robot voice might present the best arguments, but it will very likely loose to a good speaker who can (literally) tune in to his audience.

Speech is a complex pattern of sound waves, containing much more information, than binary encoded words.

So if there was a ML tool to make people with strong accent more understandable, why not. But you can also numble without any accent.

And I can enjoy and understand certain people with strong accents much better than natives, because they are just good speakers.

And having subtitles is one thing, but changing their voice .. would require consent I believe. (unless you run the tool for yourself, but I believe parents point was, he speaks and then automatically a tool enhances his voice, I would not like that, too)