[Решено] Fatal 500 error when activating string translation / WPMl og Elementor

Background of the issue:
I am trying to translate a page built with Elementor on my site скрытая ссылка. I installed the String Translation plugin because the translation doesn't show on the translated page.

Symptoms:
Activating the String Translation plugin causes a Fatal 500 error, crashing Elementor frontend and backend. Deactivating the plugin resolves the crash, but the translation still doesn't show.

Questions:
Why does activating the String Translation plugin cause a Fatal 500 error?
How can I make the translation show on the translated page without crashing Elementor?