Welcome
First the easy answers. Known problems. 1) rattle from the steering rack. Solution to replace rack. 2) Leaking a/c evaporator. Solution to replace evaporator. In my ownership my car had leaking radiator hose straight from the showroom to my house - coolant drips on my drive. Solution, Honda accepted that they had used a new hose supplier and it was not working out so all hoses including heater hoses were replaced under warranty. My car had the rattly rack (replaced under warranty) but in all of the 6 years and 85,000km never had any issues with a/c.
Now coming to the sump or oil pan being opened, who knows what happened? If the engine sounds good and nothing seems amiss, I guess you are good to go. I am guessing the t-stat has been installed. Just drive the car normally but be vigilant. Be mindful of engine temp, excessive fan running, abnormal engine noises, consumption of coolant, consumption of engine oil and so on.
Let me relate 2 stories:
1 - I bought a 1985 VW van that had a chronic over heating problem. Instead of going to the root of the problem the local mechanics kept trying to cure the symptoms. 1 - Making the fan direct. 2 - Removing t-stat. 3 - Chopping up the water pump housing and fitting a larger impeller. 4 - Rerouting water hoses to "improve" circulation. Actual problem was air locked cooling circuit caused by leaking head gasket through which exhaust gases entered the cooling circuit. I am hoping such activity has not happened to your ride.
2 - I bought a used (12000km) Chinese cross over. At around 35000 I noticed a rattling sound emanating from the left side of the engine - the transmission side. I took the car to the dealer who recorded the sound and sent the recording to the manufacturers. With guidance from the manufacturers and dealer techs, it was determined that the noise was from the flywheel/clutch assembly. A warranty claim was put up, accepted and implemented. It was an engine out job. The car has a 7 speed dual clutch transmission. Fair credit to all concerned. Indeed it was a bad clutch. Price of just the clutch was over 100k. So in this case the engine was removed and tranny separated. Basically a fairly major surgery. In this second story the car was opened up by the dealer who professionally diagnosed and corrected the problem under the watchful eye of the manufacturer.
I am hoping that in your case the basic cause has been addressed and the missing t-stat was just a precautionary "jugar".