Now about the problem:
The main language of our journal https://hsm.susu.ru is Russian. We noticed that the English version of the journal is not indexed in Google. When you switch the language on the journal page, URL does not change. The search robot will still see this page in the language that is opened by default for this Journal.
We made a plugin that allows you to add a language to the URL. After a few weeks, the English version of our journal began to be indexed by Google.
We have made a demo version of the demo.ojsonline.com
Go to the article, and on the right you can switch languages
(The article is available in three languages.)
When switching will change the URL.
The picture shows how to Google indexed URLs of articles and static pages.
Plugin tested in versions
We are also planning to attend the conference in November 2019
Our site: http://ojsonline.com
We still have problems with the indexation of Russian journals [https://vestnik.susu.ru], but we will fix it.(https://vestnik.susu.ru)