Translation:Many children are running and playing in the parks among the trees.
many children are running and playing among the trees in the park, I believe should be accepted. Reported
"Many children run and play among the trees in the parks" this should be accepted right?
the children are playing among the trees in the park- would be more likely sentence
The structure of your sentence is fine, but it's "many children" (not "the children"), and it's "in the parks" (plural), not "in the park." And they are running as well as playing.
"In the parks many children are running and playing among the trees" For some obscure reason Duolingo don't seem to like English sentences that follow the Hungarian ones too closely.
tThe "correct" translation is ambiguous. Are the parks among the trees, or are the trees in the parks?
Many children are running and playing among trees in the parks. Is this acceptable? It was marked wrong.
It should be "among the trees", not just "among trees" (you need the definite article). But otherwise, your answer is fine.