You just kind of have to be active and aware in the industry, I suppose. There isn't a single web page where it's all listed. It's a combination of things from changes in legislations, directives (EU), and a plethora of recommendations, warnings, guidance notes from regulators (central banks, FSAs) and international organizations like FATF and
OECD.
Tax residence for individuals isn't defined in
Bahrain law. But in order to get a COR, you have to demonstrate 183 days of presence in the country.
Think of it not like a proof that you're tax resident in Bahrain (since there is no such thing under local law), but rather as a proof that you probably aren't tax resident anywhere else, except for places that define tax residence more broadly than just 183 days of residence per year.