The food does not fit ON THIS PLATE, is what I'm accustomed to saying and hearing. California USA. The food does not fit IN THIS BOWL, would sound right and be correct. A plate is flat so you're putting the food ON the plate. The bowl is a container where you put (into). Hope this makes sense.
I get angry too when translation doesn't fit precisely. But we have to accept that all languages have their eccentricities and learn them by memory. When we speak small errors abroad, the local ear will be more flexibile. A site can't be as human.
Why does "nesse" mean "in/on this" for the solution, shouldn't it mean "in/on that"? Or, shouldn't the word have been changed to "neste"?
According to Duolingo usage of demonstratives, you're right.
I note that you said "according to Duolingo". Are the Brazilians like the French in that they don't really distinguish that much between "this" and "that" ?
I think "este" is "this" (next to the speaker), "esse" is "this/that" (next to the listener), and "aquele" is "that" (away from both the listener and the speaker)
I wrote "the food does not fit in THAT dish" and Duolingo accepted it as ok
Yes. In informal/spoken language it sounds very weird/formal/pedantic to use isTo/esTe/esTes/esTa/esTas/nesTe/nesTes/nesTa/nesTas/desTe/desTes/desTa/desTas. Although it's the grammatically correct translation for this, we will just stick to isso/esse/esses/... for this/that(where you are) and aquilo/aquele/aqueles/... for that (over there).
This is something very frustrating I find about Duolingo: when you're learning Portuguese, you're also learning English's irregularities. In my native language, it would be perfectly OK to say “to fit the plate”… and I'm pretty sure every English speaker would perfectly understand what I mean. But Duolingo consider that we have to speak perfect (i.e. absurdly irregular) English, even when learning Portuguese. I consider this as a very bad design of Duolingo, but well, its designers seem to want to stick to this idea.
You are correct that proper English would be on the plate not in the plate. In the plate would imply that the plate opens and the food gets enclosed within. Duolingo does not always use proper English. My guess is the person/people writing the English translation are not native English speakers and they do not know better.
"the food doesn't fit on that plate" worked for me, so perhaps they're accepting both this and that for nesse.