At the moment, interlining in Indonesia is only realistically possible with Garuda. Few airlines have the infrastructure to enable that.
As with Surabaya, the only airlines that give realistic European connections are SQ, MH and GA (and that doesn't exist at the moment). Not sure about CX's connections from the Surabaya flights. The thing about Surabaya is that the market is more East Asian oriented than Jakarta. To see how big the west bound market from Surabaya, check SQ's stats
Damn, I was hoping to get QR A332 service here soon! I have to wait I guess...