We'd have to see what the actual claims for Jordan and Lebanon are. Vilanat is not forthcoming with his actual links so I was conjecturing on what they might entail.
Like I said, the only sources I can find is that Lebanese locals attacked some refugees. Nothing about refugees being involved in any attacks.
At a minimum, it's pretty well known that both Hamas and Fatah (especially the former, now that the latter has largely renounced terror as a political weapon) have and continue to operate in refugee camps; Ain al-Hilweh is pretty famous for it, especially after Jund al-Sham used it as a base for their attack on a Lebanese Army checkpoint back in 2007, and Nahr al-Bared had to be reduced in a bloody conflict lasting half a year in the same conflict. It's good strategy, too, for the same reason Hamas uses civilian buildings in the Gaza to launch their rocket attacks on Israel; any response will draw civilians into the mess and inevitably be blamed on the attacking power, whether it's Israel or Lebanon. You have a large population of disaffected and alienated youths of prime military age, without economic prospects or political representation, who are prime for an organization that promises change through not just waiting, but actual action, making them useful for recruitment. This doesn't necessarily pertain to
Syrian refugees specifically, but as far as refugees in general, there is significant precedent locally.
That said, the particular political exigencies of the Israel-Palestine conflict do not automatically lend themselves to the use of refugee camps in the West as a base of operations for acts of political terror. I'm not certain it would automatically follow that the Syrian refugees seeking refuge in the West are terrorists, whether in part or in whole.