The indexer for eContent needs to know which languages are used in your project and whether you are using a fallback language.
Adapt this setting according to your project needs:
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silver_econtent.<scope>.languages defines the languages used for eContent per SiteAccess.
Other languages present in the database are ignored.
The second language specified is the fallback language. This means that if content is not found in the first language, second language will be used.