Hi. Thanks for your question.
I would recommend putting something in your custom details.php file — like echo "Marina details.php Test"; — to help you determineĀ if the file is actually being loaded (same suggestion for other files).
FYI: The top of each template file — e.g. /wp-content/plugins/the-events-calendar/src/views/modules/meta/details.php — typically contains a comment about the format for template overrides, like the following for the file mentioned above:
Override this template in your own theme by creating a file at:
[your-theme]/tribe-events/modules/meta/details.php
So that can help you make sure you’re placing your override files in the correct locations.
Please review this information and let me know if you have any follow-up questions. I’ll be happy to help.