I don't have a solution for your current problem, but I can tell you that the Remap Value node has curve based editing, although you lose granular control over tangents (they are reduced to None, Linear, Smooth, and Spline). This way you don't have to rely on animation curves for editing. If you've already looked into this…
Well here's a simpler way I just realized... In the Outliner window, in the Display menu, uncheck DAG Objects Only. A bunch of new nodes will appear. The ones that look like the graph editor are animation nodes. Click on one and bring up the Attribute Editor. Check "Expand Spreadsheet". There you go. :)