It's not about the amount of engineers, it's about the amount of R&D and basic research China has to essentially redo. Which includes eventually training said engineers with that knowledge.
And the corruption is less about bribes and the likes and more about businesses which don't have any expertise in the whole semiconductor area jumping onto it since it's there where all the government money is. For years a lot of funding went nowhere since the people receiving the funding literally didn't know how to actually invest into advances in semiconductor. That's improving as the knowledge what's required increases, but this whole process is essentially repeating for every single speciality ancillary industry to some degree. That's what makes the whole development very costly for China.
China is now, apparently, 3 years behind the leading TSMC node. The leading node in China today is equivalent of TSMC N5 from 3 years ago. The gap is shrinking.
It's a good idea whenever you encounter "China bad" propaganda piece (of which the Western media is full of) to be highly skeptical.
Especially the laughable propositions of "corruption" in China, coming from a country with 10x corruption - the US. You can just look at the California bullet train to nowhere, for a decade, and in the same time frame, China being able to add 1000s of miles of fast train railroads.
Or "Solyndra", the Obama era boondoggle that was to compete in solar panels, except, all the money was stolen and paid out in corruption. The list of US corruption is endless, except, in the US, it is called lobbying, providing "consulting", impact studies, regulation and regulatory compliance, litigation and litigation defense, or just plain corrupt individual at make believe jobs corruptly receiving salaries for nothing, getting the money in their bank accounts through Direct Deposit.
The same elites living off the corruption also control the press and are churning out "China is corrupt" articles. One thing you can be sure of with this crowd is the thing they accuse others of; they are already guilty of. It just takes a bit of time to process. A normal human brain is untrained for this type of deception.