After an administrator has sent a notification, they see the following message:

Notifications have been added to a queue and are delivered by a background job.

This message lacks sufficient information for administrators to review whether the notifications were successfully delivered.

Amending that message to add a link to Special:Log with log type Translation notifications log (https://meta.wikimedia.org/wiki/Special:Log?type=notifytranslators&user=&page=&wpdate=&tagfilter=&wpFormIdentifier=logeventslist) with proper wording would provide more information.