Would you consider saving/loading the data in the JSON as a feature request? I don’t understand why it would be tricky, because naively, I would think every time you load a text file, you have all the data in memory anyway.
Then you could overload Module::dataToJson() to return something like
{"sequences": [
[8.3, -5.2, 4.7, 0.1],
[2.2, 3.4, -1.4, 0.3],
[0.8, 1.1, -1.2, -3.3]
]
}
Also overload Module::dataFromJson() to decode the supplied json and put it into your in-memory data structure the same way you do when you load a text file.
People are still able to load text files any time they want to replace whatever is in memory. Plus, the next time you load a patch, it still has whatever you last loaded.
In fact, I would be willing to do the coding work as a pull request. 