Ok, i've tested the ex/import a bit. You can export a iSpark project and rename it on your computer to a ".spk" ending file, which Spark2 can import. This seems to work ok. But you can't export a Spark2 project, rename it to a ".ispk" ending file and import it into iSpark. You'll see some triggering, but there's no audio in it:-((
That's not what is suggested in the description, dear Arturia:-(