Friend is worried about language barrier at airport in France

Many airports don't announce flights at all. I can't remember the last time I was at an airport that does and I can say with confidence that London Heathrow, Amsterdam Schiphol, Detroit and Minneapolis–Saint Paul don't (yes, I know, none of those is in France).

Your friend should use information screens to determine which gate they need to go to, and be at the gate in good time – usually at least half an hour before a short-haul flight departs and at least an hour before a long-haul flight.

I think the only case where she might have an issue is if there is a last minute gate change, in which case there will be an announcement (likely in French + English and perhaps another language if the flight is going to somewhere where that language is spoken) and folks will start to migrate to the new gate.

It pays to be a bit vigilant as the expected boarding time approaches. If she is Canadian she probably understands more French than she realizes and will pick up the new gate number and flight information from the French enough to prick up her ears for the version en Anglais.

Other than that, the gates are marked in the usual way on the boarding pass (or, if not, as with early online check-in, available from monitor screens in Departures), and she will find her way to the designated gate, whether it's CDG (Roissy - Charles de Gaulle) or ORY (Orly) airports, by following the signs.

I've been to CDG (Roissy - Charles de Gaulle) airport in Paris, and they announce flights in English and French. Also the staff speaks good English and are very helpful but not smiling :). You should be OK.

I have flown through CDG numerous times over the last couple of years, most recently in April. My flights have always been announced in at least French and English.

I find CDG easy to transit, it's not bad if you're starting or ending your trip there either. Good signage, much of it in English, will help her to her gate.

Flights announcements are always done, among other few languages (French & the language(s) of your country of destination ), in English too. This is valid in all the airports of France. So no worries about that.

TL/DR - Don't rely on announcements.

I've been in places where there were no English announcements or I couldn't understand what was presumably English announcements ;). In lounges, there's typically no announcements at all.

If she's worried about missing the flight, she should go (as close as possible) to the departure gate first to know where it is, and how far.

Then, keep an eye on the time and departure boards.

98.7%, announcements at the gate will be made in several languages, English and French for sure.

While I have never been in France I have been in a lot of foreign airports. Departure boards are departure boards, fight numbers are flight numbers, gate numbers are gate numbers, times are times. Even without translation the only reason you could have a problem is if you were in a country that doesn't use our alphabet (and not always even then--when the departure boards in China are in their Chinese phase the flight number is still in our alphabet and they normally use our numbers but the city is unreadable. IIRC Japan does this also but it's been long enough I won't swear to it.) In practice I have never seen an airport that didn't show the information in English as well as the local language and I've never had any question of where I should go.