Publishing a new dataset, based on existing
I would suggest to just make the code available to generate the new features, and reference the data set you've taken from as well as the previously published methods that your code uses, rather than distributing the output.
The code is probably more broadly useful because it could possibly be used with other data, and if new versions of that data set come along your modification will be obsolete whereas your code will not (assuming the structure of the data does not change). If the combination of approaches you've used are themselves fairly novel, it may even be publishable as a paper as well, particularly if you have some results to show why doing these steps is useful in some way.
You could probably find a lawyer to argue that somehow you're allowed to do what you are proposing to do, but I don't see why. Even if technically legally allowed because of issues with considering data IP of any sort, it just feels a bit wrong to take someone's work and make it newly available with minor modification.