Earlier quoted context omitted.
The straight bars over vowels are called “macrons” in English. https://en.m.wikipedia.org/wiki/Macron_(diacritic) In Māori, there are ā, ē, ī, ō and ū.
Ahh yes there it is, thanks for clarifying. These are quite simple and would be easy to support.
Together with the macron, pinyin (the main romanization for Chinese) would be mostly supported. https://en.wikipedia.org/wiki/Pinyin