"There is water in the pond" was rejected. I think the meaning remains the same and thus the answer should be accepted
It's accepted now.
Why it can't be water is there in the pond. . . .
Because it's wrong.
Should "There is water in the lake" also be accepted given तालाब is taught to refer to both pond and lake?
It should be, you should report it.
There is water in a pond - is rejected??
We are talking about a specific pond, hence using "the"
If we used "a pond", it would be "एक तालाब" and not just "तालाब"
"The water is in the pond" was rejected. How would that sentence be written differently? To me they seem semantically equal.
The sentence is stressing on 'there is water' in the pond, whereas your statement is stressing on 'The water is'
That is my opinion, if you want, try reporting.