I think the licensing for publishing X10 games is specifically for using that engine, so if you were to use the X9 engine, you should be able to do it... I mean, the models came with your purchase, so you should be able to use them for whatever.
Of course, it'd be best to ask someone who knows what they're talking about.
The one and only,
Those who live in the past, are destined to insanity. Those who live only for the future, will be slaves to their ambitions.
Those who live in the moment... only they, are truly happy.