Translation:The eight o'clock news has a new announcer.
I have never heard of anchorwoman so I put presenter (male or female)
Sure. "Présentateur/présentatrice" = presenter, announcer, newscaster, or in gender-specific terms, an anchorman or anchorwoman. And no, you don't have to say "anchorwoman" or "anchorman". You may use the generic "announcer" or "news anchor".
I said “host” and it was marked wrong. In this day and age I don’t think it would ever occur to me to call a female TV host a “hostess.”
I'm not sure if there's a TV show in France named « Le journal de vingt heures », I put "The newspaper of twenty hours" which does not make sense for me.
Yes it is. More correctly simply France 2. It's one of several government owned channels
English is weird when it comes to gender (just like most languages!). I'd never use "hostess" for a female presenter, calling her a "host" instead. I'd only use "hostess" for a flight attendant or someone who had organised a get together.
What's the difference between my answer and duolingo answer: my answer - the eight O'clock news has a new announcer. Duolingo - the news has a new eight O'clock announcer. ???? The meaning is the same as Duo.