Yes, covering Plumeria seeds with a transparent lid or plastic wrap can be beneficial for germination. A cover helps create a humid microclimate around the seeds, which encourages moisture retention and improves germination success. The transparent lid also allows you to monitor the seeds without disturbing them. However, it is essential to provide adequate ventilation to prevent seedlings from damping off or succumbing to fungal diseases due to excess moisture. Remove the cover once the seeds start to germinate, ensuring proper air circulation around the seedlings.