Its ambiguous. The first part states you get Veneration while in an area affected by Consceration. The second states it lasts 6s.
It could mean you get affected by Veneration and retain it even after leaving the Consecrated area. Which makes sense.
Or it could mean, it lasts for 6s if you stay in the Consecrated area and vanishes if you leave it. Which also makes sense.
It really depends on what Blizzard wants this effect to do. As a quick clear for a clustered group of melee, for example, it doesn't need to persist.
Now, while I can surmise how it will likely act, and how Blizzard intends for it to act, tooltips have tripped people up before. Which part of the tooltip take precedence here is not known. Therefore we don't know for sure how it will act. It may last for 6s regardless; it may last for 6s if and only if you spent that time within the Consecrated circle.
Your interpretation is likely correct, but its far too early to say with certainty. After all, if Consecration causes veneration only to those within its area....what happens when you leave?
EJL