Chi + first name?

Helo bawb. I’ve been watching a lot of S4C ever since Covid hit and I noticed that the presenters/fictional characters tend to use each other’s first names, sometimes with ti/chdi and sometimes with chi. But since TV is not always representative of how real people speak, I was wondering: is it common to say e.g. “Sut dych chi, Owen?”? Or should I rather stick to “Sut dych chi, Mr. Jones?”? Conversely, would it be odd so say “Sut wyt ti, Mr. Jones?”?
(My native tongue is German and the formal “Sie” always goes with the person’s last name, save for a few regional variants)