That is unfortunately not correct. I grew up in a commonwealth country, have travelled to many others, and now live in the UK. Not a single person I know in either country has even the faintest idea what Fahrenheit numbers mean for temperature. It is never used in any way in these countries.
It is used for cooking in Canada even today. Here’s a UK weather report from 1987 that uses both Celsius and Fahrenheit: https://youtu.be/NnxjZ-aFkjs. Celsius is the default but there are living people in the UK who recall using the Fahrenheit scale. This is much less common outside the commonwealth.
