It seems to be correct, although it's not the same Leslie as the one originating from Scotland. According to Wikipedia, László comes from the slavic Vladislav, and is often Anglicized as Leslie. Meanwhile Louis is Hungarized as Lajos.

"Lesli" is a variant of "Leslie", both English versions of "László", which has its own variants, including "Laszlo". It is true, that one is not the other, and you can even be barred from flights in airports for having documents with different variants.

https://en.wikipedia.org/wiki/L%C3%A1szl%C3%B3

http://www.dailymail.co.uk/travel/travel_news/article-3282925/Too-blank-pages-unpaid-fines-new-hairdo-passport-banned-going-abroad.html

However, it is understandable why the course developers usually include variants of a name as possible translations, considering many people think it is a reasonable thing to do it, and do it often on daily situations.

While I am at it, personally, while I think it is important to recognize different variants of a Hungarian name, I think they should avoid testing that knowledge as often as it has been done, and return focus towards other more usual and traditional grammar questions.

That sentence is perfect, you can report it. :)

It emphasises "László": "Is it him who's playing there or someone else?", while the Duo's preferred translation is more neutral.

I translated it the same way and reported it.