I have just been looking at some themes.

If a theme has icons displayed that I don't have - could I customise the theme?

If the theme uses a foreign langauge, would I be able to change this?

In other words, are the themes 'take it or leave it' as they are.

Thanks

This will depend on the type of theme we're discussing. For Plasma themes, the system tray icons it uses will be included as part of the package. For other icons (such as for applications) you will need to determine the icon set used by the creator of the theme, and install it separately.

In terms of being intended for a foreign language - themes (regardless of being icon, Plasma or application style related) shouldn't have language strings embedded within them, so your language preferences should not be affected.