=ARRAYFORMULA(IF(LEN(A55:A), REGEXREPLACE(
 IFERROR(REGEXEXTRACT(SUBSTITUTE(A55:A, "h", ":"), "(d+):"), 0)+
 IFERROR(QUOTIENT(REGEXEXTRACT(TO_TEXT(A55:A)&"m", "(d+)m"), 60))&"h "&
 IFERROR(MOD(REGEXEXTRACT(TO_TEXT(A55:A)&"m", "(d+)m"), 60)&"m", "0m"), "^0h ", ), ))

function onEdit(e){

}

function onEdit(e) {
  var duration = stringToDuration(e.value);
  if(e.value !== duration) {
    e.range.setValue(duration);
    e.range.setNumberFormat('[h]:mm');
  }
}

/**
 * Converts a string to a Google Sheet support duration value
 *
 * @param {String} input The string to be converted
 * @returns An Integer if the input format is supported otherwise returns the input
 */
function stringToDuration(input){
  if(!typeof input === 'string') return input;
  var date = new Date(0);
  var match = input.match(/^(d.*)(.)/);
  var value = parseFloat(match[1]);
  var isDuration = true;
  switch(input[2]){
    case 'm':
      date.setMinutes(value);
      break;
    case 'h':
      date.setHours(value);
      break;
    default:
      output = input;
      isDuration = false;
  }
  var output;
  if(isDuration) {
    var oneDayInMS = 24*60*60*1000;
    output = date.getTime() / oneDayInMS;
  } else {
    output = input;
  }
  return output
}