I wouldn't say struggling so much as "not having much time"; but things like this (with events and movement scripts) seem to take a long time to develop, mainly because there's still some unknowns with the events, and even with great planning, it still doesn't always go like we expect.
Also, there's a ton of data to add. We add some, then go back and revise it, and sometimes that leads to re-working stuff again (things thought to be done before)... so it's hard to put a percentage on it.