When I rerun an import with updated image urls or image texts, the images or texts do not change
If you are re-running your import and your images do not update, chances are you have disabled the do_action calls in WP All Import or whatever import tool you are using.
If so, this means we do not get a chance to set the custom meta field ei_converted back to 0. We use this flag to tell us that there is data in the relevant fields that needs to be checked and turned into WordPress compatible fields, postmeta, media library entries and other good stuff.
To fix this, you could obviously enable the do_action calls but doing so will slow down your import and we love speed, so instead just add an extra custom field update to your import to set the postmeta field ei_converted to 0 instead of 1.
This will cause External Images to re-read the data the next time the post, product, page or CPT is used including the featured images, gallery images, variation images, variation galleries and any related alt, caption or title texts.