For me hearing the correct pronunciation while learning new words is incredibly helpful. While I don’t have any statistics on this, I feel that my success rate at remembering the correct tones is lower for words that don’t have an audio file.
Sadly there are still many words without an audio file available. Recently Hanping added the option to buy audio recordings for all the multi syllable words in HSK(1-5) and HSK 6 for a one time payment of 4.99€ respectively.
Would it be possible for you to go down the same route and license additional 3rd party audio recordings and add them as a paid addon (one time fee to cover the license costs)?