I believe they still have an office in Sofia. However, it might be not long there since the scam has been crumbling down for months.

But as you suspected, OneCoin's actual member count is most likely way smaller than the company claims. Yet this is probably the biggest international scam ever.

This graph on Google Trends reveals the harsh reality of the popularity of OneCoin. Even though the graph includes all the searches done (also by people outside the scam cult), the graph shows that OneCoin is virtually unknown when compared to the popularity of searchterm "Bitcoin".
https://trends.google.fi/trends/explore?date=2014-10-01%202017-07-11&q=onecoin,bitcoin