I am the person guilty of listing this in the accepted translations because I have encountered it. I would never say it myself, as it sounds horribly sloppy, but so do things like the abuse received by neither that your compadres never cease to report as being unfairly rejected. Long story short, too many sentences, not enough hours in a day, so I can't do a dissertation on every marginal grammar piece included in the side translations. If someone else has the energy and ability to provide the evidence for incorrectness, please do.
Authored by someone with an English-sounding last name, Google books:
Yet such a monk deprives himself of great spiritual benefit: he does not have whom to ask for spiritual counsel, for an answer to doubtful notions and perplexing moral questions[...]
Interesting. I am a native British English speaker. "Who to care for" works for me where "who" is the first word of a phrase. It's a question. Asking who to care for is therefore ok. "Who to care for" is what you're asking. Having who to care for doesn't work for me. "Who" is being used as a pronoun in the middle of a phrase here, rather than a question, and it just isn't right. Maybe Nueby's example is a misprint? Maybe some people do use it that way? What I do know is that I couldn't begin to get my head around Czech without the Tips and Hints, and for every idiot who abuses you guys there must be a dozen of us out here who are just grateful for all the hard work you do setting up these lessons and this course. Keep up the goid work!
It's possible in English, if quite rare, but whether that matches the sense in Czech here I cannot say. The nurse finds out who to care for that day at the front desk. As the desk is left vacant today, she doesn't have who to care for. "Who to care for" here does not refer to the person, but to the direction in this case not received.
FWIW, I would suggest that, in the situation you describe, to say "The nurse does not KNOW who to care for" or "She doesn't have her list of who to care for" would be more appropriate. In any case, as noted is earlier discussion, "She does not have who to care for" is no longer accepted.
The course generally does not accept "someone" in sentences like this. See the link that follows for more, especially the first and last notes regarding the use of "someone/anyone" in negative sentences and questions. https://dictionary.cambridge.org/dictionary/english/someone
Well you definitely should not be accepting "she doesn't have who to take care of". If you used "someone" like this: "Well it's because she doesn't have someone to take care of" it completely makes sense. I thought it would make more sense in this translation because koho means whom so saying "no one" isn't really a direct translation. I'm a native English speaker and I would say that someone does sound strange with out any additional info before it but the course does make some strange sounding English sentences that are accepted. Much more strange than using "someone" in this instance. So maybe you should check some of these things.
The website you cited says "usually anyone is used instead of someone in negative sentences". So I will stick to my claim that someone should be accepted. Something like "Now I don't have someone to take care of" when referring to a person who you were taking care of in the past makes sense. Someone is specific and anyone is nonspecific. You are taking these sentences out of context so you can't really say which one is more correct.
I appreciate your points about usage in negative sentences and specificity vs. non-specificity. Since this sentence, it seems to me, is both negative and non-specific, I support the decision not to include "someone" in the (nearly 700) accepted translations. Perhaps another member of the team will have a different view.
"She has no one to care for" is accepted. But there is a report in the system for "SE has no one to care for," which may or may not have been yours, that came in about the time of your comment. The hyphen in "no-one" should have been ignored. (Looks like it was, since the hyphen does not appear in the "reject" report itself.)
In this exercise, we can only pick from the words provided. My answer was not accepted because I could not really see any combination of those words which made sense as translation which in the answer above is an interpretation rather than a translation. I reported it as other reason but the system does not allow me to explain. I think the following words should be included in the options as a more accurate translation: "she does not have anyone to take care of" OK "koho" is not the same as "anyone" but otherwise my version follows the Czech fairly closely. What do you think?
"She does not have anyone to take care of" is an accepted translation. But the word bank includes the words that are in the main translation -- the one shown at the top of the page -- usually along with some "decoy" words. Apart from what is in the main translation, course teams have little to no control over what words turn up in word bank exercises. As Duo evolves, perhaps that will change...