Thanks for the clarification. To understand how the saving works, let me briefly describe how lightmix works: it creates an extra pass for each lightmix element (light or group of lights) and then one combined interactive lightmix pass. Then there's the normal beauty pass, which shows the render without the lightmix changes. So in order to save the lightmix adjustments in the image, you have to somehow save the lightmix pass.
I just tried it and the thing is that if you use "Save" in the Corona framebuffer, Corona saves the currently selected pass, so if you select the lightmix pass and click "Save", everything works fine. But if you use the C4D automatic saving, it only saves the beauty pass. To be able to save the lightmix pass as well, use the "Multi-Pass Image" tab in "Render Settings/Save". In the latter case, C4D saves all passes into a single file if the format supports it. If the format is not able to hold multiple layers, C4D saves each pass as a separate image.
What currently does not work is automatic saving in TeamRender, because of limitations in C4D. But this should be fixed in the upcoming beta release. Another thing that is being planned for later is saving to .cxr format, which can remember the lightmix settings and allows you to change the post-process and lightmix settings even on the .cxr image in Corona Image Editor.
What I would suggest for you would be the bake functionality as it allows you to have the desired light setup without using multipass. I understand that you might want to keep the original light settings, but there's an easy fix for that - use the C4D takes functionality to save the original light settings in a separate take.
Hope this helps ;-)
