Custom Post Type with Configurable Sidebar via ACF

In this situation I would use the page as a placeholder to configure the sidebars, even though WordPress will completely ignore it on the front end.

Just add the page, make sure the slug is trainings, let the client set it up as they need, and then in your template:

if ( $trainings_page = get_page_by_path( 'trainings' ) ) {
    $acf_sidebars_data = get_field( 'sidebars_acf_field_name', $trainings_page->ID );

    // Carry on sergeant
}