Certainly! Here's a refactored version of the code that makes use of variables to clarify the purpose of each step and improve readability:
```python
reserved_tokens_with_unk = ['<unk>'] + reserved_tokens
unique_tokens = set(reserved_tokens_with_unk)

for token, freq in self.token_freqs:
    if freq >= min_freq:
        unique_tokens.add(token)

filtered_tokens = list(unique_tokens)
sorted_tokens = sorted(filtered_tokens)

self.idx_to_token = sorted_tokens
```
spam fails_task lang_mismatch pii not_appropriate hate_speech sexual_content quality toxicity humor helpfulness creativity violence