I can't help with tour guides, but in case you have no luck with that, you might check to see whether the Alhambra audio guide is available in Mandarin. It's a high-traffic destination, so I'd expect the audio guide to be available in many languages.
I used the English-language audio guide in 2019 and was satisfied with it, though I have no basis for comparison with a guided tour. I will point out that the Alhambra seems to sell out on most (virtually all??) days; it's just a matter of how early it sells out. For anyone wanting to take a lot of photos and preferring that they not feature dozens if not hundreds of other tourists, it could be difficult to keep up with a guide while getting acceptable photos. Consider also that a visitor is allowed to enter the Nasrid Palaces (as well as one or two other areas of the complex) one time. If someone wants extra time in the Palaces (for photos or otherwise), they will not be able to follow the guide to other areas and then return to the Palaces later.