This language constants should only handle for Echo template instead of Office template.
This is the correct language constants which you need to create into your language override section.
OFFICE_LOGIN_PRETEXT_SLOGAN="This is a creative community of designers, artists, photographers and everyone who creates, loves and appreaciates arts in every way."
OFFICE_LOGIN_POSTTEXT_SLOGAN="Register now and start interacting with people from this community today!"