Google News sitemap keywords

[TheaterMania]

My company is a Theater news and reviews site.

We're building a google news sitemap and Google suggests some recommended keywords we can use with their <keywords>tag: https://support.google.com/news/publisher/answer/116037</keywords>

Our writers also tag their stories with relevant keywords.

What should we populate the <keywords>tag with?</keywords>

We were thinking we'd automatically populate it with author-added tags, in addition to one or more of the recommended ones suggested by Google, such as Theater, Arts, and Culture (all of our articles are related to these topics).

Finally, many of our articles are about say, celebrities. An author may tag an article with 'Bryan Cranston,' and when this is the case we're considering also tagging it with the 'Celebrities' tag.

Are all or any of these worthwhile?