Nothing necessarily easy about narrowband plus RGB stars, and with so many different ways to go about it - well there's always the potential mismatching of luminance and color.
Overall I think I like it better than the initial image. As you say, so much more of the fainter stuff (Ha, anyway) is revealed here. I suppose I might back off a wee bit, if only to not stretch out some of the mottling in the darker background regions. Also it's not standing up to full scale, but I'm pretty positive that's jpg compression artifacting.
Did you choose L, RGB as the compositing scheme, or use some Synth L from the RGB? And if so, weighted in what way?
There are a lot of potential permutations here, both in composite and later in NB Accent - which yet again allows accenting into L and/or color as per the sliders. But I wonder if keeping RGB out of the luminance might help you get some of that nebulous detail back. Or, it may not work at all, if there's nothing to color it.
Unless as an initial step you blended some Ha extract into your R? I think that's a moderately common combination to try, so perhaps not too out of control.I do recall from some previous experimenting, also discussed in a thread as others had noticed it, that "stray" light that happens to match the Ha band can end up imparting a bit of pink or red tint to places that it "realistically" shouldn't. Perhaps like the star tinting you are noting. A little bit of undo buffer on say, a star mark, seemed to remedy it.
But that's just if you want to keep playing with it.