Solved! My node is finally showing up!
The problem was that in the tutorial I was following, GetMenuEntries is used. However, there is a replacement method for it, GetMenuActions. Both are available in the K2Node API.
You need to override GetNodeTitle and GetMenuActions for your node to register properly into the blueprint system.
I haven’t confirmed this yet, but GetContextMenuActions might be used when you’re creating a compatible node from a pin from another node. If I can confirm this, I’ll update this answer.
You can find more information here.
About the Editor Module, the only naming requisite is the YourProjectNameEditor.target.cs file inside the root source folder of your project. You can name your modules however you want.