文字のインデックスの合計に基づいて文字列のリストを並べ替えるPythonスクリプトを紹介しよう：

```python
def sort_list_by_string_value(string_list):
  # create a dictionary to store the index values
  index_values = {}
  
  # loop through the list and compute the total index value of each string
  for string in string_list:
    total_index_value = 0
    for char in string:
      # get the index value for the character
      index_value = ord(char) - ord('a')
      total_index_value += index_value
    # store the total index value in the dictionary
    index_values[string] = total_index_value
  
  # sort the list based on the index values
  sorted_list = sorted(string_list, key=lambda x: index_values[x])
  return sorted_list

# example usage
string_list = ["hello", "world", "test", "foo", "bar"]
sorted_list = sort_list_by_string_value(string_list)
print(sorted_list) # Output: ['foo', 'bar', 'hello', 'test', 'world']
```
Sure. Here is a Python script that will order a list of string based on a sum of their character's indexes:

```python
def sort_list_by_string_value(string_list):
  # create a dictionary to store the index values
  index_values = {}
  
  # loop through the list and compute the total index value of each string
  for string in string_list:
    total_index_value = 0
    for char in string:
      # get the index value for the character
      index_value = ord(char) - ord('a')
      total_index_value += index_value
    # store the total index value in the dictionary
    index_values[string] = total_index_value
  
  # sort the list based on the index values
  sorted_list = sorted(string_list, key=lambda x: index_values[x])
  return sorted_list

# example usage
string_list = ["hello", "world", "test", "foo", "bar"]
sorted_list = sort_list_by_string_value(string_list)
print(sorted_list) # Output: ['foo', 'bar', 'hello', 'test', 'world']
```