If they do still have growth in the non-English congregations, they must be having some pretty bad negative growth in the English ones.
At an elders school about 7 years ago, one of the instructors mentioned that spanish-language JWs made up 25% of the US publisher figures.
In my experience, Spanish congregations typically had 3 or 4 times as many baptisms as English congregations. If anything, that ratio must be significantly higher now.
I'd venture to say that all of the growth in the US has been in foreign-language congregations - not only Spanish but Chinese, Russian, Vietnamese, Tagalog, etc.
My gut feeling is that the count of English-language congregation publishers is declining year over year, probably at a pretty steep clip, 2 or 3% down per year.
I'd also note that a lot of the "growth" in US publishers is due to immigration - JWs from other countries moving in and joining foreign language congregations.
Now that immigration has slowed, and internet access is penetrating other language groups in the US more deeply, perhaps we've reached the point that even the modest growth of the Spanish congregations is no longer enough to offset the decline of the English.