Why was Jutland transliterated as 日德兰?
日 in Jyutping (Cantonese pinyin) is  [jat6] which sounds similar to 'Ju' in "Jutland"

德 in Jyutping is  [dak1]  which sounds similar to 'tl'  in "Jutland"

and 兰 is the common transliteration in both Cantonese and Mandarin