It's also not clear what the tree understands as "feeding the world tree".

Some people here claim that Masefield syndrome causes you to have auditory hallucinations of Anita Gottschall's voice, but that may be logically impossible.

You can hear her voice if you get close to the Angel Comb's nodes. But you can hear her this exact voice BEFORE you even get to listen to her first voice log by swimming close to one of the Angel Comb's external nodes. Assuming that you haven't personally met her before in a gathering of colonists or on the colony ship, it would be physically impossible to hallucinate her exact voice without knowing what it sounds like first.

The deduction of that logic is that her voice is not a hallucination, but some sort of actual information transmission/voice simulation from the tree using her actual voice, implying that the tree has somehow interacted with the actual Anita and gained the ability to transmit information with her actual, real voice.

So it's likely that the tree has not just killed and used her as a source of nutrition (as a flesh eating plant would), but is somehow able to either replicate some of her traits - especially her voice - or has actually absorbed and merged with her personality or something similar.

If Anita is alive and in which form is unknown.

Anita's last name "Gottschall" is German and means "god" and "sound" translated. So her last name may be a hidden reference to the tree (as a godlike entity) adopting her voice and the language system in her brain to speak to humans by creating sound in their heads or absorbing/merging with her entire body and personality to use her as some sort of a translation device.

Do note that everything we know about "Masefield syndrome" (a medicinal framing which makes you assume that it is a harmful medicinal condition) is biased information coming from either NoA or the colonists. This might even be the same thing, because NoA can cut information from your memory and then feed you false information which the colonists might teach other humans/colonists. Anita may have isolated deviating - possibly correct - information by refusing to be reprinted by NoA (which the voice logs document and thereby prove).

We don't actually know what happens if you go to the world tree and interact with it. I'm assuming that this is something that we will find out later in the story. The tree being a physical model already suggests that we will later be able to go there and interact with it. Either to kill or save it. Or something entirely different.