Most residents speak at least a little English. It would help to know where in CR your friend lives. But if she's been there a while she'll know where you should go. I'd avoid the Caribbean coast, as the Pacific coast is much nicer. Go to Jaco, a great beach town with a party atmosphere. Check out the pool bar at the Cocal if you want to see what the local escort market is like. Another great town is northeast of Jaco in Tamarindo.
There are also great national parks to visit. One of the best is at Miguel Antonio, about an hour south of Jaco.
If you want additional ideas you can PM me or post again here with info on where your friend is.
Pura Vida!

Most people won't be able to open this and it's too long to cut and paste, so the link is below. The gist of it is that Colombian drug cartels have in recent years made the country their largest trans-shipment point and violence and addiction there have skyrocketed.
The worst area seems to be Limon, on the Caribbean coast, which was always a shit-hole. That said, I was there twice in 2023 and saw none of this, either in the area of Limon, or on the Pacific Coast from Puntarenas to Jaco.
Just be forewarned. I don't think there's really much of a danger to normal tourists or even sex tourists.

I've been going to Costa Rica 4-6 times a year for the last 5 years.  It's a great country. The people are always more than happy to help you hence very friendly.  (American Friendly). If you old friend is a male I'm sure he's having a helluva time
in the CR.   I have been all over Costa Rica and have had no issues at all however just like any city you need to be a bit more careful walking around at night,   If you do go get that friend of yours to take you To Baldi Hot Springs in La Fortuna.  
Pure Vida