I have ate breakfast. (今、もしくは少し前という意味で通じる？）
I have just ate breakfast.
Rosia has attacked ukraine. (今も続いているという意味で通じる？）
Rosia has been attacking ukraine for ２month.
I have bought coffee.(今、もしくは少し前という意味で通じる？）
I bought coffee A little while ago.
I have lost wallet.(今も続いている）
I lost wallet.
otani has hit a homerun. (今、もしくは少し前という意味で通じる？）
otani hit a homerun by today's game.