I'm not really deep into understanding everything but I think the gist is that Construct takes the image from the project location and turns it into a Blob which is stored on the RAM. Blobs get cleared from there of course once you close the preview again. I don't think anything gets cached. Images do get cached on exported projects, but not in preview.
So the images were only on the disk and inside the RAM. I doubt that you can recover anything from the RAM and the images on the disk have been overwritten, which makes them effectively unrecoverable.
At least as far as I understand it. So your best bet is to set everything up so this doesn't happen again (backups, version history,...) and move on. It's one of these experiences that I'd argue almost everyone will go through at some point. As painful as it is, afterwards you'll make extra sure you don't ever repeat that again.