A startup is developing a customer support chatbot for a region where users frequently blend English and Spanish in their queries. The engineering team is debating two approaches:

1. Fine-tuning a state-of-the-art model pre-trained exclusively on a massive English dataset.
2. Using a large, pre-trained multilingual model as the foundation, which was trained on corpora from over 100 languages including English and Spanish.

Evaluate these two approaches. In your response, analyze the potential effectiveness of each for handling the mixed-language inputs and justify which approach is more likely to succeed and why.