Translation:We are seeing our parents on Wednesday.
"We will see our parents on Wednesday" surely is not technically right, as "Wir sehen" implies "We are seeing" in the present tense. I suppose the addition of "on Wednesday" makes it a future action but then surely that contradicts the present tense of sehen. I would have thought that you could only say "Wir werden unsere Eltern am Mittwoch sehen."
Even though German has a separate future tense, the present tense can also be used to refer to events in the future. This is especially common in colloquial speech. Thus, both "Wir sehen unsere Eltern am Mittwoch" and "Wir werden unsere Eltern am Mittwoch sehen" are correct.
The English translation sounds a bit strange though, IMO, but I'm not a native speaker. Except, perhaps, if it referred to a habit: "On Monday, we always work in the garden. On Tuesday, we go for a long walk. We see our parents on Wednesday and on Thursday we have a romantic dinner." Would that be possible in English?
Yes you would definitely say that, although you would probably make the days of the week plural, e.g. "On Mondays, we always work in the garden." I see what you mean about using present to describe future, I never really thought about it. We do the same thing in English all the time! Although for the purpose of learning German I still think it was a bit wrong of Duolingo to put that in there at this stage.
Indeed, most would just pronounce it as Wensday. I once had an older teacher who still stuck a D sound before the N - she pronounced it as though it were spelt as Wednsday, which nearly matches the word's spelling, just with the E omitted. This pronunciation is probably on it's way out now, as I've never heard any younger person use that pronunciation.
I think this sentence is bad example. The German language have the following word order, Temporal, Kausal, Modal and Lokal. Remember "TeKaMoLo". Search for it to learn more. You can of course change the order, but TeKaMoLo is the general rule. I would say Am Mittwoch sehen wir unsere Eltern.
Would the German always be interpreted to mean a specific Wednesday, or can it also also be interpreted as every Wednesday? For "every Wednesday" in English I would probably say "I see my parents on Wednesdays," but if I threw in an adverb it might be "I usually see my parents on Wednesday." I generally wouldn't say "I see my parents on Wednesday" for a one-off future event, though I might say to my parents, "See you Wednesday." Language is confusing.
The given German sentence is about a specific wednesday (a one-off future event). If there is no context given to define which wednesday you mean, it is assumed to be the next wednesday from now on. So, when you say this on monday, you'd mean the day after tomorrow, when it is already wednesday you'd mean the wednesday next week (because it is assumed that you'd say "heute" (=today) if you mean it.).
To talk about every wednesday like "We see our parents on wednesdays." you'd say "Wir sehen unsere Eltern mittwochs." in German.
And we would say to our parents: "Wir sehen uns (am) Mittwoch!"