Often 

 there is no evidence for the article to state that Orange Order parades have "often" led to violence. The two sources don't mention it, indeed they only refer to two separate incidences in Belfast over the past year or two. The reasoning of past tense is also tenuous seeing as "have sometimes" is also past tense.

Out of the vast number of Orange Order parades a year (well over a thousand, including main demonstration and feeder), very few have any disturbances, and when they do happen it is almost always in Belfast (and usually a feeder parade of a couple of lodges), either near the Short Strand or Ardoyne. Stating "sometimes" better reflects the reality as it is not as common as the press and republicans would have people believe. How many Orange Order parades and 12ths through mainly nationalist towns have led to violence? Even during the Troubles it is in the minority. 

So unless you can reliably source that it "often" has led to violence, then the article should not state it as it is implying that it happens a lot when in reality in terms of the number of parades, it doesn't really.  (talk)