Translation:This is important to her.
"This is precious to her" was judged wrong. Please add as an acceptable alternative
So kanojo as girlfriend is not kosher on Duolingo? Getting hard to keep track of what prior knowledge holds and what doesn't.
Kanojo can mean girlfriend or just 'her'. It would be impossible to convey that it meant girlfriend on Duolingo without the context that conversation brings but Duolingo will no doubt sometimes insist you translate it one way and then at other times the other and each time mark you wrong for not implicitly knowing which definition they want you to regurgitate at any given time ; ) I would say in this instance though that kanojo simply means her as there is nothing to suggest otherwise - This (thing) is the subject of the sentence and who's girlfriend are we to presume she is with the information that is given. So, safe to assume this just means her here.
In fact "This is important for her" is just a bizarre way to say it. Actually I guess it depends. If "this" was an exam then I guess it could be important for her. Can "kore" mean something like an exam, or is it more for objects?
If the translation wanted is still "her" then why would Duo tell me it means "girlfriend" when it's not to be used yet?
Should "This is important to the girl" be an acceptable translation? (I know it's not the most natural interpretation in the world, but neither are a lot of Duo's translations for Japanese, and I can think of circumstances where someone would say it!)