When is Xcelerator reopening?

This assumes that TTD and Xcelerator both use the same catch car. Intamin may have changed the design to account for the faster launch, or even improvements from lessons learned in the first design. I couldn't say for sure if they do or not.

What’s the California agency called that essentially banished KBF’s Windseeker to Worlds of Fun? Is it actually called CalOSHA? Anyone know how to search their website or to see if they had something to do with Xcelerator’s downtime?

It's Cal OSHA/DOSH, Permanent Amusement Ride Division, they generally don't put their reports on their website from my past experience dealing with them.