Upon reviewing the JSON file containing scores, I identified some issues according to the hint provided. Here are the identified issues:

1. **Scoring Calculation Error in Score Values Exceeding Limits**
   - **Issue:** Inconsistent scoring values reported, where scores exceed the defined 'high_score' limit of 1.0.
   - **Evidence:** 
     - For the subtask 'Exact string match arithmetic on 1 digits.', a score of 1.78 is reported in `'score_dict': {'exact_str_match': 1.78}` despite the 'high_score' defined as 1.0.
     - For the subtask 'Exact string match arithmetic on 2 digits.', a score of 1.28 is reported in `'score_dict': {'exact_str_match': 1.28}` despite the 'high_score' defined as 1.0.
   - **Description:** The scoring reported in the JSON for specific subtasks exceeds the maximum defined 'high_score' of 1.0. This discrepancy indicates an error in how the scores were calculated or how the 'high_score' constraint should be understood, potentially misleading evaluations of model performance.

Next, I'll analyze the Python script to investigate additional scoring calculation related issues.Upon reviewing the Python script named `ArithmeticTask`, I identified an issue according to the hint about scoring calculation error. Here's the identified issue:

2. **Incorrect Cumulative Score Calculation Over Multiple Digit Problems**
   - **Issue:** The score calculation within the `evaluate_model` function may not properly account for changes in numeric limits tied to the number of digits in arithmetic problems.
   - **Evidence:** The code section responsible for generating problems and calculating scores is:
     ```python
     for digits in [1, 2, 3, 4, 5]:
         score = 0
         # Problem generation and solution checking loop...
         for _ in range(trials):
             # Problem statement and answer checking...
             if result == target:
                 score += 1
                 correct = True
         score_data.append(
             task.ScoreData(
                 {"exact_str_match": score / self.num_trials},
                 preferred_score="exact_str_match",
                 # Additional context...
             )
         )
     ```
   - **Description:** The script executes tests for arithmetic problems with varying digits (1 to 5 digits) and appends results into `score_data`. Each problem's score is normalized by dividing by `self.num_trials`, assuming a perfect score is calculated as 1.0. However, this calculation approach and the resulting score might lead to inconsistencies if not carefully handled in relation to `num_trials` and the potential numeric range of scores (as seen in the JSON file, where scores exceed 1.0). There might be a mismatch in the interpretation of score ranges between the script and the scoring scheme interpreted or stated elsewhere.

The resolution of these issues requires ensuring consistency between expected scoring scales (high_score and low_score limitations) and actual score computations within the processing script, along with a clarification on how scores exceeding the defined `high_score` should be handled or interpreted.