This is very interesting. I also write in English as a non-English speaking writer but I started doing so only last year (although, since I studied foreign languages in university I was used to writing essays and thesis in English) and I too wonder why I and how I feel about it. The first reason I write in English would be because breaking into the English-speaking publishing industry is easier than in my country, which is Italy. I wrote in Italian for the majority of my life now but Italian isn’t my native tongue either, it’s Croatian. But I don’t have much skill with Croatian since I never went to school in Croatia and only speak the language with my close family. So I don’t even know where I fall 😂😂 English then allows me to better express myself and it’s more nuanced than Italian or Croatian so that’s why I like writing in English