Although the downing of the MH17 flight was perpetrated by Russian separatists and not Russia itself, Moscow still had a significant influence on the separatists’ military strategy. Russia provided the separatists with political and economic support — including providing weapons and carrying out artillery attacks requested by the rebels. Russia violated the European Convention on Human Rights and needs to be held accountable for its actions.
Russia no longer belongs to the European Convention on Human Rights, so no matter what this court says, the rulings do not matter and have little standing as they can't be enforced. The impact of any ruling will be largely symbolic. Western countries are showing bias because of their support of the Ukrainian government and are trying to punish Russia for actions it had no part in.