Hello maintainer,
while translating/qs reading the German translation of your Debconf
template, we noticed the following issues:

1) You reference "yes" and "no". According to the developer reference[1]
6.6.2.4
    6.6.2.4. Do not make assumptions about interfaces

   Templates text should not make reference to widgets belonging to some debconf interfaces. Sentences like If you answer Yes... have no meaning for users of graphical interfaces that use checkboxes for boolean questions.

2)
-"another Docker distribution or want to keep data safe), the data will be "
+"another Docker distribution or want to keep data), the data will be "

The word "safe" is confusing. Is it normally kept unsafe?

I suggest running your template via debian-l10n-english, as per [1] 6.6.2.1:
please use (and abuse) debian-l10n-english@lists.debian.org mailing list. Have your templates proofread.

Finally, we were not sure if this question is needed after all. Purge
is a well defined concept, why you do offer users the possiblity to
apply it nor not? Or do you extend the purge to some data not owned by
the package?

[1] https://www.debian.org/doc/manuals/developers-reference/best-pkging-practices.html