WordPress Multisite Multilingual Setup Guide
Since WordPress 3.0 it is possible to set up a WordPress Multisite installation. Among them is a collection of pages that share the same WordPress installation. You can also share the same themes and plugins. The individual pages are virtual pages in the sense that they do not have a directory on your server, even though they have different directories for media and different tables in the database.
This allows you to create a website in different languages. The main advantage of this is that you use the core functions of WordPress, so it is very safe and free to use. advantages
The main advantage over the WPML plugin is that WordPress is always installed in one language. This means that you can have a first address (mydomain.com) and a subdomain or subdirectory for the Spanish version (or es.mydomain.com mydomain.com/es). This also applies to all other languages.
If you manage multiple sites across multiple domains, you can use WordPress MU Domain Mapping plugin, as long as the domains all hosted on the same server.
It is also an excellent opportunity for large and complex sites, as few compatibility problems occur and it costs very little.
Disadvantages: It is more difficult to manage. First you need to create a network of pages using the multisite features.
If you make a change, you have to import it every time in the other theme. By two is not a problem by three it starts to be difficult.
Also, it can happen that not all plugins run without errors on multi-site environments.
WordPress Multisite was not originally intended to create multilingual sites.
The translation management of the content is intensive because you can easily lose track of what has already been installed and what is not.
In the meantime, new plugins have been developed to minimize this. Multisite Language Switcher, Zanto, Multilingual Press. These plugins allow you to synchronize the files. For example,if you want to link the translated content and avoid that you always land on the home page when you switch between languages.
Conclusion: an excellent option for large WordPress sites, but difficult to configure and manage.