Sunshine's search widget has never been all that advanced as Sunshine's primary use case is not for stock photo sites. However, in the 2.8.16 update, this search process will be updated!
Sunshine will loosely match any title or description for the image. So for example, searching "car" would return an image if it's title is "Woman wearing scarf".
Sunshine by default will pull any EXIF data and save it as metadata - it has always done this and data like keywords embedded in the images do get saved! However, in this update, searches now will also search for exact match image EXIF keywords - so "car" will only match "car" keywords and not match "scarf".
Small changes to keep making Sunshine better!