Oh yeah, it was there, I just missed it.
If I was wording it, I think I would just use an easier to read sentence structure. "Javelins can be moved through by other models. If a model moves through a javelin during a move action, the moving model may displace that javelin at the end of the move." Or something like that. But as long as you know what it means, that's what matters.
For LOS, how about something simple but fun, like "The path of the javelin is considered to run from the center of the throwing model's base to the center of the target's base. If this path passes through any other models on the way to the target, roll a dice for each model in sequence. On a 4+, it hits that model instead of the target."
For hazards, you could distinguish between blocking or obscuring. A blocking hazard would be like a big boulder, that blocks LOS completely. An obscuring hazard would like like a fence or something - maybe give a 4+ chance that the javelin hits the fence instead of the target, if the target is behind it.