Hi @helga19 ,
Thank you for the tag!
I’ve never eaten kholodets, but your explanation and photos got me interested in trying it out. 
There’s a similar dish in the Bulgarian cuisine, called ‘pacha’ (or ‘пача’ in Bulgarian). I admit that I’ve never cooked it myself, but as far as I know, we mostly use pork–feet, ears, head.
Another difference is that we can eat pacha hot, when it’s liquidy like soup, or cold, when it turns into jelly, just like kholodets.
Can you find kholodets in restaurants in Russia? Or it’s more of a homemade dish?