I have Fedora 23 Cinnamon Spin running on my laptop, which is great, I think.
But I like to have my system language set to English, while I prefer the rest of the locale ( time and currency formats for example ) to
be set to Dutch ( I want 24 hours clock and the euro as currency ).

In this spin, I just could only change the language, not the individual locale settings, but I’ve found out how to fix this.

Just enter
gsettings set org.gnome.system.locale region nl_NL.utf8
( Or any other locale, really ) to change this for your user.