[已解决] How to read a custom field in translated language

Background of the issue:
I am trying to translate a custom field in a WordPress post using WPML. The original post is at 隐藏链接 and its translation is at 隐藏链接. The first widget is a simple Heading Elementor text field configured to read the custom field named 'Nazwa Kursu'.

Symptoms:
In the preview, the title reads correctly as 'carpentry from scratch', but after publishing, the title remains in Polish. When I edit the English (translated) post manually, the custom field is in English.

Questions:
How can I make the title read the correct custom field in the translated language?
What is the step-by-step procedure to ensure the custom field is translated correctly?