That's because яка means "what/what kind of." And it corresponds to the gender and number of the noun it modifies: який (m) яка (f) яке (n) які (pl). Яка книга ти читаєш? (What kind of book are you reading?) Які фільми ти любиш? (What kind of movies do you like?) Яке це пиво? (What kind of beer is this?) Який хліб ти любиш їсти? (What kind of bread do you like to eat?" Generally these are used when "what kind" can be substituted for "what." So it's який for (what/what kind of) and що for only (what) I'm not a native speaker, but hopefully this helps.
If someone is still traveling, you would say "how is your trip", or "how is your trip going" or slightly more awkwardly "how are your travels going". Once they get back you would say "how was your trip", or slightly more awkwardly "how were your travels". I think it's good that the lesson currently accepts several different translations, but it does feel strange to use past tense in a present tense lesson.
Yes, I think in Ukrainian this question is only in present tense and is asked if the trip is ongoing. If we want to ask about a trip in the past we would say "Як пройшла ваша подорож?".
I would rather remove the past tense from here because I don't think it makes much sense.
My only guess is, this answer was added because people were claiming "How was your trip?" is a way more common sentence, but simply because we ask about past trips more often than ongoing, not because it's a more common translation... I would remove it :/