I don’t think you have the right approach for this problem.
Here, you’re talking about 4 domains, not subdomains. Subdomains are what usually replace the www in an url.
And, if you create a multisite network, then you won’t need to have a multilingual plugin since you plan on having only one language per website.
Having a multisite network is useful if you plan on having a different content for each website of the network. However, if you plan on having the same content in different languages, then I’ll advise against it.
If you want to have the same content in different languages, you should only create one WordPress website with a multilingual plugin such as WPML or Polylang. It will save you some time as translating a page/post is easier than recreating it on another website.
Regarding the website url for each language, it’s also easy to set up. I know that at least WPML includes this natively and gives you tutorials to set up your DNS for that purpose.
So, as a result, I would suggest :
- Create a single website with a multilingual plugin
- Setup your different domains to redirect to a specific language version of your website