You know what I struggle with? Writing professional letters (or email) in my native language. I went to university and worked in the industry in the UK and so I only ever had to write in a professional style in English. I was trying to ask for some information from an online shop in Greek the other day (I'm Greek) and I found I had no idea how to start and end the email and how exactly to phrase the question I wanted to ask without sounding like I was talking to my bestie.

Kind of the reverse situation than what you're describing, because I haven't learned to say those things in my native language, but for me it goes to show we learn lots of pre-baked turns of phrase that we adjust appropriately to the context when we need them.