Thank you for your feedback, and we sincerely apologize for the inconvenience you're experiencing.
You're absolutely right — at the moment, SP Page Builder does not offer a dedicated custom field type for audio files within the dynamic content framework. Your current workaround using a rich text field is a practical interim solution, but we understand the limitations, particularly with the default behavior of audio playback and the lack of styling control.
Based on your suggestion, I’ve gone ahead and submitted a feature request to our development team for a dedicated audio field, similar to the existing video option.
Thank you for your patience and understanding — and for helping us improve SP Page Builder with your insights.