If you mean a trick where Affinity Publisher is fooled to replace images in one go by using a renamed folder, note that when you get a warning about missing images, you need to select "Yes" from the dialog. Using Resource Manager does not allow you to actually replace images but just locate the saved but missing ones in a different folder (which I think that Walt does above).
Replace_trick.mp4
UPDATE: So what you assume, that there is something extra that Publisher uses to match an image must be true, mere filename is not enough.
One (simple?) thing I'd love to see is the ability to create a shape (rectangle, circle etc) with specified dimensions. In Illustrator, you can click with the appropriate tool and it then asks for a width/height or radius and creates it at the spot you clicked. To do the same in Designer, you have to drag out a shape and then edit its dimensions in the Transform panel which means more steps.
garudha got a reaction from mobabs in Shape Tool: Click to create specified size