Farrell played the entire match as the Parisians gained their third win of the season. He did not score any points as scrum-half Nolann Le Garrec took the kicking duties and booted 17 points.
"I'm feeling comfortable. I feel like I've been here for a while now. I feel like I'm more and more myself," Farrell said, speaking in English at the post-match press conference.
"The language is still a little bit of a barrier at times, but I feel I'm understanding more what's being said. I listen a lot and there's a lot that speak very good English in the team. I've got to speed up my French, so I can get points across quicker."
The club's attack coach, Frederic Michalak said Farrell was "on the way up", and learning the "Racing 92's style of play and way of playing with panache".
Elsewhere, leaders Bordeaux-Begles scored 10 tries as they pulverised Perpignan 66-12 with Matthieu Jalibert, Enzo Reybier and Romain Buros all touching down twice.
They moved five points clear of La Rochelle, who crashed 37-7 to Bayonne in San Sebastian as Farrell's former Saracens and England teammate Manu Tuilagi, returning after suffering a pre-season hand injury, made a convincing Top 14 debut.
Tuilagi made his presence felt when he flattened France captain Gregory Alldritt, a 1.91 metre (6-foot-3) No. 8, with a 32nd-minute tackle.
Bayonne's other centre, Fijian Sireli Maqala, scored his fifth try of the season with a spectacular dive, making him joint Top 14 top scorer with Damian Penaud of Bordeaux-Begles.