The Eventon plugin only works correctly in the admin panel, that is when the user is logged in. If the user is not logged in, the events are only visible in the primary language (Swedish)
2. Diagnostic
Please ensure that you have enabled the following configuration option:
WPML > Languages > Language filtering for AJAX operations > Store a language cookie to support language filtering for AJAX
This should be checked and saved.
Does it resolve the problem?
For new plugins, we ask the assistance of our clients to recreate the problem on a sandbox site that we can provide for you. You will be asked to upload the plugin and configure a simple example that illustrates the issue. I will then confirm it and see if I can identify a workaround. I will then send the site to the compatibility team who will then work with the author of the plugin to provide you, our mutual client, with a solution.
You must appreciate that this can take time and if we do not have the collaboration of the plugin author, it can be that we do not find a solution.