Odoo11 replacing field in sale.report_invoice_layouted with a custom module - odoo-11

Question

I'm creating a custom module for odoo 11. I would like to add information to the customer invoices. I tried changing the sale.report_invoice_layouted which inherits report_invoice_document. Changes i made in sale.report_invoice_layouted Qweb are visible when printing the pdf. For example I change the field l.name to l.price_unit and this works.
But no I created a custom module and have this template.xml
<odoo>
<data>
<template id="report_invoice_document_tenure_inherit" inherit_id="sale.report_invoice_layouted" priority="16">
<xpath expr="////span[#t-field='l.name']" position="replace">
<span t-field="l.price_unit"/>
</xpath>
</template>
</data>
This has no effect at all. Nothing is changed in the printed pdf. I checked "Reload attachment" and it is set to off.
Any ideas on what I'm doing wrong?
Edit:
this is the original sale.report_invoice_layouted which I'm trying to change via module:
<?xml version="1.0"?>
<data inherit_id="account.report_invoice_document">
<xpath expr="//table/tbody/tr/td[#id='subtotal']" position="attributes">
<attribute name="groups">!sale.group_show_price_total</attribute>
</xpath>
<xpath expr="//table/tbody/tr/td[#id='subtotal']" position="after">
<td class="text-right" groups="sale.group_show_price_total">
<span t-field="l.price_total" t-options="{"widget": "monetary", "display_currency": o.currency_id}"/>
</td>
</xpath>
<xpath expr="//table" position="attributes">
<attribute name="groups">!sale.group_sale_layout</attribute>
</xpath>
<xpath expr="//table" position="after">
<t groups="sale.group_sale_layout" t-foreach="o.order_lines_layouted()" t-as="page" name="lines_layouted">
<table class="table table-condensed">
<thead>
<tr>
<th>Description</th>
<th class="text-right">Quantity</th>
<th class="text-right">Unit Price</th>
<th t-if="display_discount" class="text-right" groups="sale.group_discount_per_so_line">Disc.(%)</th>
<th class="text-right">Taxes</th>
<th class="text-right">Amount</th>
</tr>
</thead>
<tbody class="invoice_tbody">
<t t-foreach="page" t-as="layout_category">
<t t-if="layout_category_size > 1 or page_size > 1" groups="sale.group_sale_layout">
<tr class="active">
<td colspan="7" style="font-weight: bold; border-bottom: 1px solid black;">&bull;
<t t-esc="layout_category['name']"/>
</td>
</tr>
</t>
<!-- Lines associated -->
<t t-foreach="layout_category['lines']" t-as="l">
<tr>
<td><span t-field="l.name"/>
<span>TEST</span></td>
<td class="text-right">
<span t-field="l.quantity"/>
<span t-field="l.uom_id" groups="product.group_uom"/>
</td>
<td class="text-right">
<span t-field="l.price_unit"/>
</td>
<td t-if="display_discount" class="text-right" groups="sale.group_discount_per_so_line">
<span t-field="l.discount"/>
</td>
<td class="text-right">
<span t-esc="', '.join(map(lambda x: x.description or x.name, l.invoice_line_tax_ids))"/>
</td>
<td class="text-right">
<span t-field="l.price_subtotal" t-options="{"widget": "monetary", "display_currency": o.currency_id}"/>
</td>
<td class="text-right" groups="sale.group_show_price_total">
<span t-field="l.price_total" t-options="{"widget": "monetary", "display_currency": o.currency_id}"/>
</td>
</tr>
</t>
<t t-if="(layout_category_size > 1 or page_size > 1) and layout_category['subtotal']" groups="sale.group_sale_layout">
<tr class="text-right">
<td colspan="6">
<strong>Subtotal: </strong>
<t t-set="subtotal" t-value="sum(line.price_subtotal for line in layout_category['lines'])"/>
<span t-esc="subtotal" t-options="{'widget': 'monetary', 'display_currency': o.currency_id}"/>
</td>
</tr>
</t>
</t>
</tbody>
</table>
<t t-if="page_index < page_size - 1" groups="sale.group_sale_layout">
<p style="page-break-before:always;"> </p>
</t>
</t>
</xpath>

Answer 1

Replace your code:
<xpath expr="//t[#name='lines_layouted']//tbody/t/t[2]//span[#t-field='l.name']" position="replace">
<span t-field="l.price_unit"/>
</xpath>