Because everything in Node-RED is based on node.js packages, you can simply take your own fork of a node if you need to make some tweak to it, you can then install your own version. That gives you the added advantage that you will be able to track changes to the original over time to see whether you still need your fork or whether you need to update it.
Of course, if your proposed change might help others, it is the neighbourly thing to do to offer your code change back to the author so that they can decide whether to include it in the original. To help with that, it is best to raise an issue against the original explaining what you need so that the author has a chance to respond.
