Apply a function to dynamic children from an API call

I've created the custom action like so:

// Automatic FlutterFlow imports
import '/backend/schema/structs/index.dart';
import '/backend/schema/enums/enums.dart';
import '/flutter_flow/flutter_flow_theme.dart';
import '/flutter_flow/flutter_flow_util.dart';
import '/custom_code/actions/index.dart'; // Imports other custom actions
import '/flutter_flow/custom_functions.dart'; // Imports custom functions
import 'package:flutter/material.dart';
// Begin custom action code
// DO NOT REMOVE OR MODIFY THE CODE ABOVE!

import 'package:timeago/timeago.dart' as timeago;

String convertTimestampToFuzzyTime(
  DateTime? timestampDateTime,
  String? timestampString,
) {
  var timestamp = timestampDateTime;
  if (timestamp == null) {
    if (timestampString == null) {
      return '';
    }
    timestamp = DateTime.parse(timestampString);
  }

  return timeago.format(timestamp);
}

So I'm almost there, but I can't apply an action to each child of a dynamic list. I could do this with a function on rendering the text, but I can't import timeago as part of a function 🙁

Is there a way to do this? Do I need to do something like an API Interceptor? That seems a bit heavy-handed!