I think all the foreign language groups and congregations are to give the illusion of growth to those in the US and other developed countries. Those that join are usually pioneers or are bored in their congregation. ASL congregations have exploded over the last decade. Most ASL congregations have about 50 publishers, but only about 10 deaf who regularly attend and maybe 2-3 deaf publishers. We constantly here about how much it's growing, but it's mostly from hearing people joining.
On a side note, I think ASL is the reason why tablets finally were allowed and utilized throughout the org. We've been using them since the fist iPad to show videos and it's been the only thing most brought to the ASL meetings for quite a while.