unequalsine

Aswell as a temporary fix –> If you want go a step further and change the week-names into your wordpress language you have to edit two files.

In plugins/woocommerce-local-pickup-time-select/public/class-local-pickup-time.php change line 289 through 299.

Old

$today_name = strtolower( date( 'l' ) );
$today_date = date( 'm/d/Y' );

// Create an empty array for our dates
$pickup_options = array();

// Loop through all days ahead and add the pickup time options to the array
for ( $i = 0; $i < 7; $i++ ) {

// Get the date of current iteration
$current_day_name = date( 'l', strtotime( "+$i days" ) );

New

$today_name = strtolower( date_i18n( 'l' ) );
$today_date = date( 'm/d/Y' );

// Create an empty array for our dates
$pickup_options = array();

// Loop through all days ahead and add the pickup time options to the array
for ( $i = 0; $i < 7; $i++ ) {

// Get the date of current iteration
$current_day_name = date_i18n( 'l', strtotime( "+$i days" ) );

And in plugins/woocommerce-local-pickup-time-select/admin/class-local-pickup-time-admin.php use find and replace to change all english weekday-names into your desired language. This has to be done very precise, so make sure you spell the names correctly.

Hope this helps