"Almost all A-H dual-listed companies are relatively overvalued in A-share market and undervalued in H-share market, and it has been the case for the last 10 years."
This may reflect the lower value of non-exportable yuan.
China is a huge captive market with few investment options, actually. Your choice is either to figure out how to get your money out into a convertible currency, invest in bubbly real estate, or play in a market with heavy insider trading problems.