the current python reference solution produces nonsense for those inputs, and those inputs might not make very good sense either.
js produces similar input cases, so it would be nice if author could fix that first before moving on to the other languages

I encountered the same problem. There seems to be an issue with the random tests where the last layers of a landscape have too few characters. The solution for those random tests ignore the coloumns with missing characters alltogether.
Example:
Input string:
"ABC\nDEF\nG"
The provided solution would be:
"A\nD\nG"

Good catch! Indeed. I added random tests that make your naive solution fail systematically (the solution is to choose n small enough) to all languages but Haskell (I left a message to the translator so he can revise his translation if he feels like).