Thanks so much! I downloaded latest dev version and it seems to be functioning a lot better. 
In VapourSynth under Artifacts, I now notice RemoveDirt and RemoveDirtMC. Did you add those filters relatively recently? Because I didn't really spot them in the prior version. Also, I saw your post about enabling Merge with RemoveDirtMC so one can better control it and so it doesn't operate too strongly on the image. I tweaked a few settings after I saw your screenshot in IMGbb. I think this filter can be highly effective for older films as long as I don't put it in overkill.
In VapourSynth under Artifacts, I now notice RemoveDirt and RemoveDirtMC. Did you add those filters relatively recently? Because I didn't really spot them in the prior version. Also, I saw your post about enabling Merge with RemoveDirtMC so one can better control it and so it doesn't operate too strongly on the image. I tweaked a few settings after I saw your screenshot in IMGbb. I think this filter can be highly effective for older films as long as I don't put it in overkill.