They are most likely not switching language in their phone - you can see it with the full width punctuation. In Chinese mode, typing English is a little annoying to get case right. A lot of Chinese people don’t differentiate between case also.
To be totally fair, I have no memory of what kind of comma they used and the fullwidth one that I used represents an assumption by me. What stuck in my mind was the casing.
But other than that, yeah, I came to basically the same conclusion that you give here.
