but still how can be such a difference between core and package temperatures?
There shouldn't be. It's something you are, or are not doing.
https://www.techpowerup.com/review/silentiumpc-spartan-3-pro-rgb/6.html
^Those are test results with that cooler paired with an 8700K - overclocked and non-overclocked samples. Out of the 8 scenarios, the cooler causes thermal throttling in pretty much 3 of them.
All 3 of those scenarios were stress tested + OC'ed, where the 8700K is capable of dumping around 200w of waste heat; the Ryzen 1200 and 2600X don't come anywhere close that.
The 1200 may push 70w(worst case scenario), and the 2600X, 110w(again, worst case).
I've checked the specs of the Silentium PC cooler. It's rated for 150w of heat; the 2600X is well within it's capability to cool.
You appear to have mounted the cooler correctly - and reapplied paste as well. If you hadn't, your idle temps would've been much worse, like 45C or something.
my case is a kolink luminosity
OH.
Take the front and side panels off and run Cinebench R20 again, please.
How high do the cpu temps get?