Obsidian uses the operating system’s commands for undo and copy/paste. CNTRL + Z is thus a global command. It works on my non-English keyboard as well. If your keyboard is Cyrillic, this function must be mapped to some corresponding letter in the alphabet and a quick search on the internet will yield the answer.
You can also install the Editing Toolbar plugin and use the undo and redo (CNTRL + Y) buttons from there and can also map the hotkey from that plugin to CNTRL + Z like I did:
