(this is specific to Z-library)
Russia is out. Some books on the platform directly contradicts government ideals, and it seems that the operators aren't willing to filter it out.
China might be a safe case, but recently they have cared for IP (at least for literary things, industrial processes are another matter) because they have multiple industries that China saw as beneficial (both audiovisual and literacy, including comics) so they could evade US authorities but might get sentenced by Chinese authorities anyway.
I don't know enough about Cuba to comment.