X265 slow preset further adjustments modifications?

[YaBoyShredderson]

In trying to encode 4k hdr blurays in staxrip, with transparency as the goal. I use the slow preset and crf 20 ssim tune (using this for testing, will get rid of once ive settled on the settings).

Is there any further adjustments i can make in staxrip to improve things a little bit further without going to far into the diminishing returns territory? And without slowing things down to a crawl (more of a crawl than it already is).

Another question, im trying to retain hdr, and ive selected the hdr injest option, thinking i need this to do it, but its producing 2 files at the end with slightly different mediainfo information. "Name"_new.mkv looks normal in media info. But the second file "name_new.mkv_hdr10.mkv has different mastering display luminance, max cll, and max fall, with an aditional line under each, saying the original information. Which on of these is correct?