Thank you for the screenshot, and yes you are right, it is a Memrise official course, isn’t it! That is actually the old course that we no longer update. We have the following new updated course now.
The old course is mostly taught in Hiragana, even when you would use Kanji or Katakana in real like, as you pointed out earlier. This was the team’s approach when they first created the course for the purpose of easing in the users. The updated courses, especially the script ones have a more practical approach. If the words are written in Kanji in Japan, they will be written in Kanji, because that’s how you would actually see it in real life. However, you may find this a bit brutal as it expects you to learn Kanjis from very early stages and many of them at the same time. This point is soon to be addressed in our upcoming new system. I’m hoping to make the marking less strict so that user can type in hiraganas if they don’t know the correct kanji.
For now, to answer your original question, if you go to the new courses, you will see those items (coffee, banana…) in Katakana. I would also recommend the new course because all the errors found in the old courses are fixed there, whereas the old course does not get updated anymore. Hope that help! Thanks!