I've configured our Magento 2 transactional emails, they are sending correctly and content is mostly correct. We use Royal Mail for most shipping and the Magento order shipment is automatically updated with a Royal Mail shipment reference and included in the order shipment email for each despatch.
The default order shipment template includes the shipment reference and also the text label 'Tracking number', this will obviously lead to customer confusion as it isn't specifically a tracking reference. The email tracking link is linked to our website rather than Royal Mail tracking and displays the shipment reference, no tracking details.
My question is; where can I find the text labels and links used in the email template in order to correct them? I'm assuming this line is calling the information I need to edit:
layout handle="sales_email_order_shipment_track" shipment_id=$shipment_id order_id=$order_id