I reply below to some points but only to share better my point of view I tried to wrote in the article.
> I'm not sure if more linguistic diversity will help FLOSS.
I think linguistic diversity in FLOSS means a more accessible FLOSS world to people that not speak English.
> For countries with more English speakers (e.g. most European countries) I don't think translations provided to developers will prove beneficial.
But here in Europe (I'm from Italy) not all country have the same level English skills. I also wrote the article thinking to the whole World with so meny country with a low level of instruction.
> The language-mastery issue is real, especially for very young people, but I'm not sure if "forcing" people isn't the better call.
I don't think in the article I wrote about forcing people.
> The suggestions for more simplified English in the article seem like good ideas to me.
Thanks, I'm happy you found the idea good.