But the burning question I have is:

32 year old Johnny English is adopted by Taiwanese parents/parent and takes on ROC nationality and the Chinese name of Li Chen. Does his British passport become irrevocably invalid? Or does he retain the right to (resume) his British nationality and the ability to still be Johnny English while simultaneously enjoying the privilege of having a Chinese name and holding a ROC national ID card?

It raises an interesting point. Foreigners who choose to take a Chinese name when they obtain ROC nationality and have that name in their Taiwan passport and who may have the ability to resume their former citizenship or obtain another citizenship or who may already have a 3rd citizenship which they need not renounce, can end up with two legal names, a Chinese one and their other one. All you have to do is go back to your previous country and open a bank account in your Chinese name or even get a driver’s license in your Chinese name and on paper you are two people.

Two different driving records, two different credit files, two different passports, all in two names. But in reality, they both belong to one person. But the system will treat them as two different real individuals.