How to filter a taxonomy meta field to the ‘single_term_title’ filter hook

Solved the issue by passing the term_name as a parameter to the callback function to the filter.

function bn_term_title( $term_name ) {
    $term_types = get_term_by( 'name', $term_name, 'tax_1' );
    if( $term_types->taxonomy === 'tax_1' ) {
        if( get_locale() === 'bn_BD' )
            return get_term_meta( $term_types->term_id, 'tax1_bn' );
        else
            return $term_name;
    }

    $term_categories = get_term_by( 'name', $term_name, 'tax_2' );
    if( $term_categories->taxonomy === 'tax_2' ) {
        if( get_locale() === 'bn_BD' )
            return get_term_meta( $term_categories->term_id, 'tax2_bn' );
        else
            return $term_name;
    }
}
add_filter( 'single_term_title', 'bn_term_title' );

The code can be more concise when get_term_by() will make the $taxonomy parameter optional. If the taxonomy parameter become optional we can do it like below:

function bn_term_title( $term_name ) {
    $term_types = get_term_by( 'name', $term_name );
    if( get_locale() === 'bn_BD' )
        return get_term_meta( $term_types->term_id, 'term_bn' );
    else
        return $term_name;
}
add_filter( 'single_term_title', 'bn_term_title' );