It seems that when doing a “copy/paste of nodes”, we don’t know where the “past nodes” will be placed into the node editor … something random ? or do you know a way to do to past somewhere precisely ?
It should be pasted into the same position (x,y) as the node-tree you copied from, although if you’re working with a large node-tree it can be a bit confusing. - You can try Zooming-to-Selected(?) by pressing , (or .) on your numeric keypad, it should zoom into the nodes you just pasted (if they’re still selected)