If you want to translate reports then you need to define two templates:
1-The main report template
2-The translatable document
And follow the follow the following step in given below->
you can go to Settings Reports Report Search associated QWeb views <translatable_document> Associated translations.
And change the view in report you can see the below code .

</translatable_document></report_name>
<Main template>
<template id="sale.report_saleorder">
    <t t-call="report.html_container">
        <t t-foreach="doc_ids" t-as="doc_id">
            <t t-raw="translate_doc(doc_id, doc_model, 'partner_id.lang', 'sale.report_saleorder_document')">
        </t>
    </t>
</t></template>

<!-- Translatable template -->
<template id="report_saleorder_document">
    <t t-call="report.external_layout">
        <div class="page">
            <div class="oe_structure">
            <div class="row">
                <div class="col-xs-6">
                    <strong t-if="o.partner_shipping_id == o.partner_invoice_id">Invoice and shipping address:</strong>
                    <strong t-if="o.partner_shipping_id != o.partner_invoice_id">Invoice address:</strong>
                    <div t-field="o.partner_invoice_id" t-field-options="{&amp;amp;quot;no_marker&amp;amp;quot;: true}">
                &amp;amp;lt;...&amp;amp;gt;
            <div class="oe_structure">
        </div>

</div></div></div></div></div></t></template>