"This cruise looks bad, but you chose it."
Translation:Cette croisière a l'air nulle, mais tu l'as choisie.
Mine was rejected as well. I typed "cette croisière a l'air mauvaise, mais vous l'avez choisie" and I believe that is a legit translation so I reported it.
I got it in English. Did you get it originally in French? What the French sentence above says is "This cruise has a lame air, but you have chosen it." (To "have an air" of something is to appear or seem to be something.) For example, "She seems fatigued" can be expressed in French as "Elle a l'air fatiguée".
In this case the cruise (croisière) seems "nulle" which is the same as the English word "null". But we tend to use the word "null" only in Geometry or Algebra classes, where it means void or empty. (e.g., the intersection of the set of odd numbers and the set of even numbers is the null set.) The French use it where we would say "lame". (e.g., the cruise was lame.) Well, that's US English. I'm not sure whether other varieties of English use the word "lame" like this. Lame literally means crippled.
So, a reasonable translation of the French sentence would be "This cruise looks bad, but you chose it." But I think other translations are possible.
It's just the usual problem of synonyms in translation. There might be 5, 10, or even 20 different words that mean about the same thing. This is especially true with adjectives. It's also especially true in the English language with its huge lexicon.
Thesaurus.com lists 46 synonyms for "bad". Probably 20 of them could have been used in this sentence. And they don't have all of the possibilities. They don't list your "lame", for example.
It makes sense that the staff who created this lesson listed a couple of these synonyms in the algorithm. It's also almost humanly impossible that they could have listed all of them. They might have listed 29 synonyms, but "lame" was the 30th one and it didn't get listed.
So how do we users deal with the incompleteness of accepted answers. For starters, I think it makes sense to use the most common "standard" words in our answers. That might bring us down to 4 or 5 reasonable possibilities for translating nul. If you choose one you feel is reasonable, but it isn't accepted, by all means report it within the lesson.