To confirm, you are using different images on the different language versions of the posts, not just translating the texts associated with the images (like alt text), yes?
Can I check how you are inserting the images on the page?
I suspect that if you were to just insert the image on a test page you make with the block editor and translate the page the correct versions of the image would appear, and that the issue arises because of how the image is inserted.
It looks like the image is inserted in something other than a standard Elementor module (screenshot).
Would it be possible for me to get access to your site so I can check exactly how the image is added. I need to be sure of that to be able to try and reproduce the problem.
Let me mark your next reply as private so that I can get log-in credentials from you—you may want to create a temporary admin user for me to use that you can later delete. And be sure to have a current backup of your site.
I was able to confirm that the images are added via the Timeline widget of the Qi Addons for Elementor plugin.
I tested the issue on my own local test site and was able to reproduce the issue.
The problem arises because the WPML configuration file included with the plugin by its authors does not include handling for the images.
We have a tool available to generate custom XML to configure custom widgets, and I generated an updated wpml-config.xml for the Timeline widget, but that still did not work.
I've asked my colleagues in the compatibility team to take a closer look. Hopefully they can suggest an update to the configuration for the widget so that it works (and then share that with the plugin authors, too).
I'll get back to you when I have an update from them.
You will also need to add some PHP to your site. The best way to do that would be with a plugin like Code Snippets, or you could add it to the functions.php file of a child theme.
This is the code you'll need (it only needs to run on the front end, which you can specify with the Code Snippets plugin):