Correctly handling multi language URL's in sitemaps

Question

I have an English page:

https://www.example.com/content/article-1

This page is also avaliable in other languages at the URLs:

https://www.example.com/de/content/article-1
https://www.example.com/zh-hans/content/article-1
https://www.example.com/en-gb/content/article-1

My sitemap currently only lists the English pages. The English page has the meta tags:

<link rel="canonical" href="https://www.example.com/content/article-1" />
<link rel="alternate" hreflang="de" href="https://www.example.com/de/content/article-1" />
<link rel="alternate" hreflang="zh-Hans" href="https://www.example.com/zh-hans/content/article-1" />
<link rel="alternate" hreflang="en-GB" href="https://www.example.com/en-GB/content/article-1" />

If we visit the German page, the meta tags are:

<link rel="canonical" href="https://www.example.com/de/content/article-1" />
<link rel="alternate" hreflang="en-US" href="https://www.example.com/content/article-1" />
<link rel="alternate" hreflang="zh-Hans" href="https://www.example.com/zh-hans/content/article-1" />
<link rel="alternate" hreflang="en-GB" href="https://www.example.com/en-GB/content/article-1" />

If for example the zh-Hans translation is incomplete/bad quality, we put <meta name="robots" content="noindex"> on the page itself.

Questions

• Are the canonical and alternate links correctly set up
• Regarding sitemaps currently we only have one listing all the English URLs. Is this sufficient? Or should we have a sitemap for each language? It is fiddly to establish sitemaps for all languages, but if there's any benefits to doing it I'm happy to do it.
• Will the noindex page 100% ensure Google doesn't index the page even if the URL appears in alternatives/sitemaps etc? (We don't want to be penalised for bad quality/incomplete translations)

Answer 1

• yes, they are correct
• to have all language versions in the sitemap doesn't influence indexing. it influences the crawling not much too, because the crawler gets an access to other language versions through rel="alternate" hreflang links. but to have all language versions in the sitemap, like it shown there, helps on debugging - if anywhere anything becomes buggy, Google notifies you about it. from this point of views i would recommend to include all language versions into sitemap. Specially because it seems to be not tricky for you, if all of urls in english version have their counterparts in other language versions.
• noindex is enough :) protect against poor quality filters/penalties