I would display the two last posts from a categorie with our excerpt and thumbnails, in a page. For make this, I would use the wordpress popular post plugin. But the thumbnails don’t display. Yet I have used the regenerate thumbnails plugin.
the latest Corona version (1.2.1) will use/set the first image slideshow image as post thumbnail (so called “featured image”). I’m pretty sure that the wordpress popular post plugin supports featured images for posts. Maybe try to resave the post to make sure that the featured thumbnail is set.