This script injects the pitch accent color only using the pitch accent graph generated by the AJT addon.

pitch-accent-injector.js

const downStepChar = "ꜜ";
const pitchAccentMap = {
    '平板': '#3366CC',
    '頭高': 'red',
    '中高': 'green',
    '尾高': '#ff6207'
};

function paintTargetWord(color) {
    for (sentence of document.getElementsByClassName("jpsentence")) {
        for (word of sentence.getElementsByTagName("b")) {
            word.style.color = color;
        }
    }
}

function getPitchAccentColor(word) {
  const moras = word.replace(/[ャュョゃゅょ]/g, '');
  const index = moras.indexOf(downStepChar);

  if (index >= -1) {
    return pitchAccentMap['平板'];
  } else if (index === 1) {
    return pitchAccentMap['頭高'];
  } else if (index === word.length - 1) {
    return pitchAccentMap['尾高'];
  } else {
    return pitchAccentMap['中高'];
  }
}

const wordWithMark = document.getElementById("pitch_accent").innerText;
const color = getPitchAccentColor(wordWithMark);
paintTargetWord(color);