Shall I localise and translate Schema.org structured data into each available language?

Question

Let's say we have a website that is offered in English and German. Assume the Services offered -

{
"@context": "http://schema.org/",
"@type": "Service",
"serviceType": "#{t('TRANSLATION.MARKETING')}",
"provider": {
"@type": "LocalBusiness",
"name": "#{Settings.brand.company_name}"
}

-- are available in UK, Ireland, Germany, Austria and beautiful Switzerland (hence, content is available in both EN & DE).

Should we add the structured data both on EN & DE pages in English, or shall we translate it into each respective language?

Example - Translated JSON-LD with LocaleApp (Ruby on Rails):

"areaServed": [
{
"@type": "Country",
"name": "#{t('generals.united-kingdom')}"
},
"@type": "Country",
"name": "#{t('generals.ireland')}"
},
"@type": "Country",
"name": "#{t('generals.austria')}"
},
"@type": "Country",
"name": "#{t('generals.germany')}"
},
"@type": "Country",
"name": "#{t('generals.switzerland')}"
},
]

or just keeping it simple and tag in English (on both EN & DE):

"areaServed": [
{
"@type": "Country",
"name": "United Kingdom"
},
"@type": "Country",
"name": "Ireland"
},
"@type": "Country",
"name": "Germany"
},
"@type": "Country",
"name": "Austria"
},
"@type": "Country",
"name": "Switzerland"
},
]

I am split about this, given the information is for search engines, and to make sense of the content (Semantic Web). Of course anything tagged on a page needs to correspond to its content (according to Google Best Practice). However, JSON-LD remains something we feed to SEs and not the user. So by that logic, offering it in English should be sufficient. I have not been able to find a clear answer to this.

So if anyone has a link that confirms the best practice that would be amazing - or perhaps has experience with multilingual pages.

Answer 1

Google Guide Managing multi-regional and multilingual sites tells us:

Use different URLs for different language versions

Google recommends using different URLs for each language version of a page...

This means that your versions for English and German content must have separate URLs.

Another Google guide Follow the structured data guidelines tells us the following:

Relevance Your structured data should be a true representation of the page content.

Thus, your structured data for separate web pages in English and German must have content in the language of the content of the web page to which this data refers.

Added 2019-10-01 due to the new user question:

I may display user content as country "Österreich", while structured data says "Austria".

Check the following information for the addressCountry property of Schema:

The country. For example, USA. You can also provide the two-letter ISO 3166-1 alpha-2 country code.

Use the name and alternate name properties for your country data. For country identifiers, use the property additionalProperty and the embedded type PropertyValue. E.g.:

> "@type":"Country", 
> "name":"Austria", 
> "sameAs":[
> "http://vocab.getty.edu/tgn/1000062",
> "https://en.wikipedia.org/wiki/Austria",
> "https://de.wikipedia.org/wiki/%C3%96sterreich" ], 
> "alternateName":[
> "Republic of Austria", 
> "Österreich", 
> "Republik Österreich" ],
> "additionalProperty":{
> "@type":"PropertyValue", 
> "unitCode":"AT",
> "sameAs":[ 
> "https://en.wikipedia.org/wiki/ISO_3166-2:AT",
> "http://dbpedia.org/page/ISO_3166-2:AT" ] }