Hi,

Kindly check the below code for reference.

<template id="report_saleorder">

 <t t-call="report.html_container">

   <t t-foreach="docs" t-as="doc">

   <t t-call="sale.report_saleorder_document" t-lang="doc.partner_id.lang"/>

   </t>  

  </t>

</template>

Here, we are taking the pdf report based on the partner language. For that we are using the ‘t-lang’ . If you are not required to use the partner language or user language. You can create a field for saving the required language value to the model. And mention that corresponding field name on the t-lang attribute of the inherited template.

Hope it helps