from what i can tell, wadoku is a dictionary and has the associated accuracy. However commercial access to their data is not for free and you would need to contact them to find an agreement that is agreeable with both parties.
Generally they require companies integrating their dictionary into commercial software to give them a share of the total income, but I assume this is more for using all of the dictionaries content and you could get something better as you only want the pitch-accent information.
their licence is completely in german and they seem to have two licences making things more complicated
anyway you could try contacting them, i think the following page contains the best current email:
Alternatively, I know that on apple devices the standard installed dictionary comes with pitch accent information. you could try contacting the publisher of that as well