'fair' is correct and usable in written English. You can use it as an adjective meaning 'just and reasonable' or as a noun meaning 'an event where goods are sold or displayed'. For example: My friends and I split the cost of dinner fairly. I was excited to see the selection of art at the county fair.
It's a fair point.
We will ensure that these programmes are a fair representation of what took place throughout their stay".
That's fair.
Harsh, but fair.
But is it fair?
Western observers have never deemed any Uzbek presidential or parliamentary election in the post-Soviet era to be free and fair.
"It's not fair.
Since I tried Ludwig back in 2017, I have been constantly using it in both editing and translation. Ever since, I suggest it to my translators at ProSciEditing.
Justyna Jupowicz-Kozak
CEO of Professional Science Editing for Scientists @ prosciediting.com