2005 Honda Odyssey catalytic converter

No, I wouldn't believe that at all. A Catalytic Converter is not going to cause a timing belt failure. Poor maintenance and not replacing the belt when recommended will cause that but it looks like you were right on time with that one. Assuming no one previously worked in the timing belt area, I don't see a reason for failure.

What really happened to the engine?

Did the timing belt broke and was the engine fault related to the timing belt?

Was it due to lubrication faults?

I concur with Wrenchtech about the catalytic converter not being the cause even if it is any of the problem I mentioned above.

Were the repairs done at a dealer?
Was replacement of head before or after the timing belt replacement?

the timing belt caused the engine to basically blow up. We had the head work done at the same time as the timing belt being replaced. The work was not done at a dealer but a local mechanics workshop. I think all of the problems occurred due to shoddy work done the first time. We had the new engine and everything installed by a Honda Dealership.

Yes, I would agree workmanship error is most likely to be the cause. Too bad it occurred after a period of use so it is not easy to get the workshop to take any responsibility.