Translation incomplete

Got the latest German .po-file and editied it, to more closely follow current German spelling rules. You can find it here.

There are still some translations missing to complete version 9.4, like for:
Email
Date
x items
Restrict the number of recipients per email to (0 for unlimited):
86400 seconds
Jetpack Weekly [Engl.]
Notification email (must not be empty):
a reference style list of links at the end of the email with corresponding numbers in the content
(for the full content plain text per-post email only)
a list of post titles followed by links to the articles
(for digest emails only)
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What do I need to do to be able to translate those as well?

https://ww.wp.xz.cn/plugins/subscribe2/