2007 Honda Odyssey Long term effects?

The dealer says the motor mount and the torque converter failed. They want to send a sample of fluid in to be tested to see if I need a whole new transmission.

I drive children on field trips often and safety is huge. I want to ensure the mechanic at the dealership has double checked everything and replaced all that should be replaced. What items do I need to ask him about to sound halfway knowledgeable and protect my self from future issues?

I am not sure of the engine size.

Thank you.