I've been exposed to 'train' primarily as referring to game elements, like 'I rode the Mundo train up to gold rank' or similar. But then, I don't MMORPG; it's probably different in a raiding/PVP/guild environment.
As for the cliffhanger...that's the thing. I'm not concerned. There appears to be nothing at stake at this point, so I have little reason to worry that anything will be lost. Apart from being mildly concerned about what Hwan Sung-Gon is up to (because the story told me not to be urgently concerned), I don't feel any tension in the narrative.