The model-based key determination approach can be enhanced by integrating a more sophisticated emotional analysis framework that considers the nuances of musical expression. One potential improvement is to employ a multi-layered neural network that not only predicts the key based on the emotional condition but also incorporates contextual features from the melody and historical data of similar compositions. This could involve training the model on a larger dataset that includes a diverse range of emotional expressions across various keys, allowing it to learn the intricate relationships between specific keys and their emotional connotations. Additionally, incorporating reinforcement learning techniques could enable the model to iteratively refine its key predictions based on feedback from generated outputs, thus aligning more closely with the desired emotional valence. Furthermore, integrating user feedback mechanisms could provide real-time adjustments to the key selection process, ensuring that the generated harmonies resonate more effectively with listeners' emotional perceptions.