Other people will no doubt have opinions on this, but I think the channel match tool is probably not the right thing to fix this, rather you need to look at your alignment process, as John says.
There's multiple different ways to get there, but here is the process that I use:
1. Choose the best of the luminance subs, and use that as the alignment reference in the Star Align tool for all subs of all channels. Since my RGB subs are binned 2x2, aligning them using a 1x1 binned luminance reference also takes care of the interpolation at the same time.
2. Integrate each of the separate stacks of channel subs to get my R, G, B & L frames.
3. Combine of the RGB, keeping L separate.
4. With RGB and L frames open, temporarily create a combined LRGB frame. This shows the limits of the combined stack where there are parts of the edges not covered by all subs due to misalignment.
5. Open a Dynamic Crop tool, and draw a box in the temporary LRGB frame that encompasses only fully covered areas.
6. Drag the new instance icon from the Dynamic Crop onto each of the L and RGB frames.
7. Save the cropped RGB and L and discard the temporary LRGB.
At this point, I have cropped and registered L & RGB frames to do further work on, that I can (much) later combine with the LRGB Combine tool.
