The only time not to transliterate a name faithfully is when the name is almost certainly an unfaithful transliteration of non-Japanese in the Japanese.
Examples of unfaithful transliterations in the Japanese are 「アルマ」 for “Alma” and 「ベルナ」 for “Berna”. I've seen translations fuck-the-monkey and just take these to be “Arma” and “Beluna”.
「メル」 should not be rendered as if 「メリ」; that would have been a faithful transliteration of “Merry”.
Transliteration is not translation; “Barbold” is not a word in English; and Japanese cannot faithfully transliterate “Barbold”. If you gave the Japanese, one of us might suggest what to make of it; but, in any case, wholesale changes are not appropriate.