daniL

Problem:
getting some random 404 pages trying to access to the events in the secondary language.

Solution:
The TEC adds the option to translate the slug of the events as an admin string. However, this is not the correct way of doing this. The value should be translated from the post type translation of the slug in WPML > Settings > CPT Translation > Set different slugs in different languages for Events.

Once you MATCH the values there - then it works.

Relevant Documentation:
https://wpml.org/documentation/getting-started-guide/translating-page-slugs/