Asumaru

“Multisite Language Switcher” is very attractive plugin. 
However, It may not be available for your site plan.
<ul>
<li>Site A (English) example-site.com/</li>
<li>Site A (Japanese) example-site.com/jp/</li>
<li>Site B (English) example-site.com/siteB/</li>
<li>Site B (Japanese) example-site.com/siteB-jp/</li>
<li>Site C (English) example-site.com/siteC/</li>
<li>Site C (Japanese) example-site.com/siteC-jp/</li>
</ul>
“Multisite Language Switcher” cannot tell the difference between site A, site B and site C. 
Therefore you cannot connect the language when there are site A, site B, site C.
“MSLS Grouping” adds “group_key” to settings of “Multisite Language Switcher”. 
For example, you set “group_key” with “SiteA” or “SiteB” or “SiteC”. 
You can limit a language site in a group by doing this plugin. 
You can display only the first site when there are multiple same language sites in a group.
And, it provide shortcode “SameLangSites” and widget “SameLangSites”. 
You can output the list of different groups of the same language. 
For example, “SameLangSites” of “site A (English)” lists ” site B (English)” and “site C (English)”.
<ul>
<li>Site A (English) => Site B (English), Site C (English)</li>
<li>Site B (Japanese) => Site A (Japanese), Site C (Japanese)</li>
</ul>
And, it provide “Language” column on the Table of Sites in network.
And, it provide “Language Flag” in Admin-Bar.

MSLS Grouping

You can multilingualize by "Multisite Language Switcher" with grouping the sites of the plural same languages.

edouardb

WTIpress makes a WordPress site multilingual, and lets you translate posts and pages using the <a href="https://webtranslateit.com" rel="nofollow ugc">WebTranslateIt.com</a> service.

wtipress

Makes a Wordpress site multilingual, and lets you translate posts and pages using the WebTranslateIt.com service.

MSLS Grouping vs wtipress