I agree with you about not being able to get hiragana and katakana, but it was very manageable to travel through Japan with no dictionary . I also carried a notebook where I was writing Chinese and showed it to random Japanese people and they almost always got the meaning. Obviously your first example is a bit mean, because you’d know what a Chinese speaker would interpret it like. But this sentence won’t exist in the “wild”. The second example is a bit easier to get. A lot of assumptions are coming with this “on the fly” translation. For example I played dark souls in Japanese but I don’t speak it. It was manageable to play when there were enough Kanji, because of how items were shaped etc. A lot of assumptions but it kinda works