Even though it is a different node that has focus when the cell is in the editing mode, I think it still makes sense to users that the TableView keeps the focus ring. Users don't care the editor is a separate node. They only care that the table should always have focus in editing mode or in non-editing mode. The current behavior is even worse as sometimes the Cell has focus but not the editor (such as TextField) even when the editor is visible. In this case, the table actually has the focus ring.

I haven't tried on an editable TreeView and ListView but I assume it applies to them too.