Are there smaller ticket offices in Paris that handle the purchase and booking of tickets rather than going to the larger stations to do so?
I believe you can get tickets at travel agencies.
These days, most people are buying them with an app on their phones.
The SNCF Connect app is very easy to use if you will have a smart phone with you and it can save you from standing in line. Last year, I easily bought tickets through the app. It is handy as you will get alerts about train delays and track changes through the app.
You'll have a better chance of getting someone fluent in English at the ticket office in a large station.
Of course having said that, the one time I went into Gare du l'Est for tickets, no one spoke more than basic English. So we combined that with my basic French (and previous online research) and voila, two tickets.
I know it's not a direct answer to your question, but we were just in Paris and Normandy. The SNCF website is user friendly, and the app is even better; you'll have your tickets right in the app.
What’s the question behind your question? What train ticket do you want to buy? From where to where? And are you aware that the ticket machines have an English language option?
This might help
https://www.sncf-voyageurs.com/en/travel-with-us/prepare-your-trip/travel-agencies/
For the record, I understand why you might want a ticket office. Occasionally you can get stuff there you can't get online, or you CAN get online if you know the right codes. Why I'm attempting something complicated I'll visit a ticket office