Does this legitimately mean what the English translation says? To me, the function of 'exactly' here is to modify the 'why' rather than the 'come' (it reminds me of the Japanese いったい which is a dedicated word for this concept). To convert 'exactly' to 'gxuste' and insert it in the middle of the sentence seems to yield a strange meaning, i.e. 'why did you come here in an exact manner?' Whether it actually translates properly is dubious to me. Cxu ekzistas Esperantistoj kiuj denaske parolas aliajn lingvojn, kaj kiu povas respondi mian demandon?
Glad to see others are wondering about this translation as well. I luckily got it right, only because my experience with Duolingo Esperanto has caused me to try and understand what the writer of the question was wanting to say in addition to how I might initially translate what I just heard/read.