Suineder
The transliteration of モード for "Maud" is based on the name being pronounced in an accent that does _not_ exhibit the "cot-caught merger":https://en.wikipedia.org/wiki/Phonological_history_of_English_low_back_vowels#Cot.E2.80.93caught_merger. In such an accent, the vowel in "Maud" is an "open-mid back rounded vowel":https://en.wikipedia.org/wiki/Open-mid_back_rounded_vowel (or close to one), which sounds similar to Japanese お. However, the voice actors are almost all Canadian, and most Canadian English accents have the merger (a bunch of US accents do, too).
You can see the same sort of effect in, say, the transliterations of words starting with "auto-", like "automation" (オートメーション).
Regardless, モード is what most artists (and presumably fansubbers) have settled on.
You can see the same sort of effect in, say, the transliterations of words starting with "auto-", like "automation" (オートメーション).
Regardless, モード is what most artists (and presumably fansubbers) have settled on.