Reliable in the sense that those who were confirmed as covid-19 and died were counted. It's well known that people who died when the health system was overrun and who weren't tested for the virus aren't part of the official count.
Currently we have 700,000 cases around the world with several epicentres in lockdown. The death count stands at 33K. There's no reason to believe Wuhan by itself had 40K cases. The response in the mainland was also very different. Quick lockdown in other parts of the country, mandatory mask wearing, people not working due to extended CNY break, and China sending 20,000 doctors into the epicentre. Hence you see a very different result than what you're observing in other continents.
I really don't fully understand the total anti-China bias on here. Sure, the CCP do many awful things, but I'm not sure this virus response is necessarily one of them. They acted slowly, yes. (Show me a European country that acted fast? Look at the USA ffs. ). Like every country that finally figured out shit was hitting the fan, they then did something about it, and what they did seems to have been effective.
Have they tested everybody? NO. (Who has?)
Do they have their own definitions of confirmed cases and deaths? (Yes - so does everyone else)
Did they change definitions? Yes. (And so you should, if you realise there is a better way).
Are they hiding thousands of dead people? I don't know. I can't imagine that would be easy. Media may be controlled in China, but bad stuff usually gets out.
Are they hiding one or two dead people from time to time - probably. It would be consistent with how they operate to fudge facts a little. But as long as it's not a lot, does it really matter that much?