A limited attempt to make parts of Omeka multilanguage
Install the plugin in the usual Omeka way.
In configuration, you can select the languages into which your site could be translated (see Limitations below).
You can also select the elements (applies to Items and Collections), that are translatable. If something like Dublin Core Identifier is made translatable, you will make me cry.
The plugin should respect browser settings for preferred language. Alternatively, it plays well with the Guest User plugin to allow guest users to select their preferred language.
From the plugin configuration screen, check the elements that will be available for translation. This will apply to Items and Collections.
Also, select the languages available for translation. The edit screens will add clickables to add a translation for those elements.
Those links just display the not-always-transparent locale code. Basic training will be needed to teach translators which codes correspond to which languages.
Simple Pages and Exhibits can be assigned a language code from the Multilanguage Content tab. For a multilanguage site, you will have to recreate your pages and exhibits in the new languages.
Omeka has its own system for i18n of core admin text. This plugin does not address core text in any way.
Language options are based on the existance of core translation files.
The translations submitted via the admin screens MUST exactly match the original language element content. Any edit to the elements MUST be followed by a new translation for each value. That is necessary to allow for translations of multiple values for each element (e.g., multiple subjects, each one translated).
It might work well to solidify the base language text, then do translations. But all workflows differ.
Of course, the translation itself need not actually be a translation of the text -- it could be completely original text in another language -- but it will always have to match with base-language text.
The Dublin Core Title element is tricky. In the flow of filters down to Multilanguage, it is already translated from '[Untitled]' into a target language.
Interactions with other plugins might produce unexpected results.
Simple Pages and Exhibits can be assigned a language code from the Multilanguage Content tab. For a multilanguage site, you will have to recreate your pages and exhibits in the new languages.
If the plugin is installed, Simple Pages and Exhibits content will disappear without updating the language assignments from the Multilanguage Content tab. Each new SP or Exhibit requires a language assignment from that page.