I have serious doubts whether this kind of data is even copyrightable, as long as you're not redistributing it verbatim.

A specific selection of words with pitch data (e.g. the NKH pitch dictionary) might be copyrightable as there was creative expression involved in picking which exact words to put into the dictionary and in what order. But the data itself? A 猫 is always going to have a HLL pitch accent (in the standard accent). That's a fact. And facts itself are not copyrightable.

You can't copyright a phone book[1]. Quoting from the case:

> "Notwithstanding a valid copyright, a subsequent compiler remains free to use the facts contained in another's publication to aid in preparing a competing work, so long as the competing work does not feature the same selection and arrangement"

Sounds exactly like the pitch accent data dump that's been floating around which a lot of people use. (Not the verbatim NHK one; the other one.) They probably used the data from NHK's pitch dictionary to compile it along with a few other dictionaries. But does it feature the same selection and arrangement? Nope.

[1] - https://en.wikipedia.org/wiki/Feist_Publications%2C_Inc.%2C_....