I understand the issue you're having and will try my best to assist you in this matter.
Indeed the link on the button should get updated automatically but, if you later modify the slug of the primary page, the link will not adjust on its own. Please try the following steps and check if that helps to solve the issue.
- Since the 'RESERVEZ UN SERVICE' button is a part of the Elementor Header template, please open the default template in Elementor Editor
- Remove the link from the button and add it again in relative format['/service-category/']. Since you're using Elementor PRO, it would be better if you could link the page with the button using the Dynamic field feature of Elementor.
- Save the changes, exit from the Elementor editor, and try to update the translation of the template by following the instructions here: https://wpml.org/documentation/plugins-compatibility/elementor/#translate-elementor-templates
Please let me know if that helps to solve the issue or you need further assistance in this matter. I will be happy to help.
