Direct Bondi, is some what correct with regards to the engine situation, you just have to look at any other 787 operator to see the current on going engine difficulties with the Rolls Royce Trent 1000, so why would Norwegian be any different.
So the upgrade is probably to solve the engine problems, or to hit the problem head on before it becomes an issue.
The Wamos operations are no doubt there to cover the short fall and delays caused by the JFK snow storm, as with any low cost carrier schedules are tight, and really have very little room built into them for significant delays.