Upvote:3
Answering to what extent they investigate is hard. The answer is a combination of the duty of the embassy officers to make sure travelers obey the laws and the screening time, as they have a lot of applicants to screen per day.
Governments do not generally exchange all detailed personal information according to privacy laws. If they did, a new datagate would blow up. But there are indeed a lot of private data bases that governments can buy for money, plus a few tax exchanges that I know of.
Cheating at interviews is relatively easy as you may still deny to have been more than 6 months in China, but if your current passport shows a Chinese visa with entry/exit prints, no officer is denied to check every single passport page to verify your documentation. On the contrary, if they find a record that you have been in China for more than 6 month you will probably be banned from that country for a long time.
I generally do not recommend ignoring the laws, but you have to know that, for example
I could speculate on the existence of your name / DOB on any private record indicating that you may have lived more than 6 months in a country. I currently have no source so I won't expand speculations. Anyway it is not certain that they will eventually find out. But mind the consequences if they do!!!!!