Translation:We are not going to the car, but to the water.
I think not - I think that would be felé rather than -hez.
"going towards something" indicates the direction you take when you start moving, but does not necessarily imply that you reach the destination.
Compare "He took a step towards me", which almost certainly means that he was not at my side after the movement is over.
I personally would say this could be an accepted (alternative) translation.
But first and foremost the Hungarian should be flawless, because this is the language we want to learn here. English should just match the meaning. If this is backwards I am fine with it. Sounds weird but I at least get it, is the important thing. And for that neither forest instead of woods, nor kindergarten teacher instead of nursery school teacher can be an actual problem for any native English speaker and non natives too (as long as it is consistently "wrong"). Problematic are those translations that actually confuse, because they say something different than Hungarian. Everything odaall, ideül or the discrepancies in tenses/cases would need a more natural and complex English approach than just trying to mirror every word.
The main problem with Duolingo is that a translation will be accepted only if the exact sentence happens to have been entered by the course creators into the database of valid answers (with some wiggle room for typos). So if the purpose of an exercise is to translate an English sentence to Hungarian, then I think your argument makes sense, and might even be helpful because the odd construction of the English sentence would remind us of how to construct the Hungarian translation. But with the reverse translation, you really need to have natural-sounding English, because that is what a user is going to write. If an unnatural sentence is the only correct answer, nobody will ever get it right.
Having "not ... but" here and "nem ... hanem" there sounds like it helps in both directions what the program expects? And as I said we want to learn the nem/hanem (or hoz here actually) not that English approaches it with the "positive" part first?
So it might be unnatural, but I don't think anyone has had an actual problem with those elements here as far as I read discussions.
Lots of people do have trouble with translations to English because Duo expects specific responses, and it's hard to remember, not to mention guess (for the first time), what it expects. I've heard many people complain that they have to write down the odd (but correct, according to the exercise) English sentence, so they can type it in and progress in the skill. This can be frustrating and tedious, and some people give up. I think there should be as many valid, natural English translations as possible for H->E translations. In the other direction, it's not so important to have perfectly natural English, as long as the meaning is clear.
Essentially I agree, as I said, it sh/could be included if I would have a say in it. Everything that includes the same meaning should be considered alright.
I am kind of perplexed by the quality after 800k people have at least started the course and all the talk about the database already being filled to the brim. Some of my (imho obvious) reports have been accepted in the past weeks. As though either way too many people did not report and only commented (the comment section is not bursting either), or way too many reports have been declined in the previous months.
It is correct in the form of a „not X but Y” statement, as it is with „either X or Y”. We go either by car or by train. We go not by car but by train. Commas can be added for a little shift of emphasis: We go, not by car, but by train. Widely used with „to be”: This is not a funnel but a tundish ((c) James Joyce). If you want to use an auxiliary verb, you must repeat the verb: We do not go by car, but we go by train.
If you had your examples match the sentence, I'd be a bit more convinced. :´)
But I think "We go not to the car, but to the train" sounds just awful. Archaic. Too poetic for the purpose. "We stride not back, but towards progress!" is a bit more fitting, but still weird.
The verb "to be" is exempt from the need of an auxiliary verb in negations and questions, so you don't even need to dig out a Joyce quote. It is not a big hurdle, but we should not slack either.
Also what's wrong with "We do not go by car, but by train"?