Alright, well there’s nothing that you can do about the enumeration. It’s not exposed to reflection so it can’t be exposed directly to blueprint.
Option 1) Don’t include it as a parameter of the UFUNCTION. Given how you’re using it you can probably make a reasonable assumption about what it’s value should be globally in all cases. It looks like it controls behavior to select or jump the view to the new node, which makes sense when making one but if you have a script making multiple it doesn’t make as much sense. So you could remove it from your function and hard code in the None value.
Option 2) As RecourseDesign points out, it’s basically just an integer. You can have your function take a integer or byte and cast that to the enumeration. It’s looks like it’s a bitwise value so that makes it tougher to match up the values.
Option 3) Make you’re own enum that is blueprint accessible that has the same values as the NewNodeFlags. At least then you can include it in your function and add all the bitflag markup so that the blueprint UI does all the hard work for you. In native you’d still have to cast it.
Personally, out of those options, I’d go with option 1.