Go to Computer\HKEY_CURRENT_USER\Software\Unigraphics Solutions\Standard Parts\Version 110 & here you will see the following registry key: "RuntimeLanguage", double click on it and edit its value from 1034 to 1033 in decimal mode.
I just tested that language of ST10 Standard Parts is also dependent on ST10 language.
For example: If I use my local language (czech), I have Standard Parts in local language. If I switch language to english in SE Options - Helpers tab - Use english language, after ST10 is restarted Standard Parts are in english language.
I do not know if Standard Parts can be set to different language from SE as for ST9 or older versions.