A Debian user brought this issue to my attention: In the spanish localization (gentext/locale/es.xml), the translations for keys beginning with an uppercase also begin with an uppercase and the same translation for the lowercase key begins with a lowercase. E.g.
<gentext key="Article" text="Artículo"/>
<gentext key="article" text="artículo"/>
Comparing this to en.xml this seems to be a mistake, that needs to be corrected.