How should English reference be cited in a non-English work?
For what concerns citations there is a general international standard, the ISO 690, but at the moment I don't have access to it. Therefore, I'll give you an answer based on an Italian style guide and on a number of Italian and French popular science books, from different publishers, that I have on my bookshelf (e.g., [1-7], but I can find many others).
All books report English, German and French references in the format

Authors, &quot;Original title,&quot; Journal Date

No translation of the title is provided. The translated title is reported only for books which have an Italian edition too.
Il nuovo manuale di stile (The new manual of style), edizione 2.0, by Roberto Lesina, §15.4, explicitly says

I titoli di scritti in lingua straniera vengono sempre espressi nella lingua originale.
Titles of writings in foreign languages should be always expressed in the original language.

There's no distinction between academic and popular science books.
Books [1-6] are written by Italian and French authors; [7], instead, is a translation of the original Russian edition, and there are Russian references. These are not translated either, but the Cyrillic letters have been transliterated. This is in agreement with the recommendation of the cited style guide for titles in non-Latin alphabets (§5.4.3).
To sum up: I think that there is some, possibly strong, evidence, from at least two countries, that references in popular science books should be treated exactly as references in academic works.
[1] G. C. Ghirardi, Un'occhiata alle carte di Dio, Il Saggiatore, Milano, 2003.
[2] M. Ageno, Le origini dell'irreversibilità, Bollati Boringhieri, 1992.
[3] R. Lamouline, Du Thermomètre à la temperature, Éditions Ellipses, Paris, 2005.
[4] J.-P. Parisot, F. Suagher, Calendriers et chronologie, Masson, Paris, 1996.
[5] G. Lolli, La crisalide e la farfalla. Donne e matematica, Bollati Boringhieri, 2000.
[6] A. Guerraggio, P. Nastasi, Matematica in camicia nera. Il regime e gli scienziati, Bruno Mondadori, 2005.
[7] V. I. Arnol'd, Huygens &amp; Barrow. Newton &amp; Hooke, Bollati Boringhieri, 1996.