Filter Algolia items based on a string attribute? [InstantSearch]

Clash Royale CLAN TAG#URR8PPPFilter Algolia items based on a string attribute? [InstantSearch]
I'm trying to make a work around to a multi-language search different than this options, I have a field in my records 'language', I now I can filter based on a timestamp, i.e:
filters: 'timestamp < 1532681390'
But I cannot get this to work:
filters: 'language:en_us'
Am I missing somethign? Do I need to add language someplace else?
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