magento-test/app/code/Magento/Translation/Test/Mftf/ActionGroup/StorefrontFillCustomTranslationFieldActionGroup.xml

<?xml version="1.0" encoding="UTF-8"?>
<!--
 /**
  * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
-->

<actionGroups xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
              xsi:noNamespaceSchemaLocation="urn:magento:mftf:Test/etc/actionGroupSchema.xsd">
    <actionGroup name="StorefrontFillCustomTranslationFieldActionGroup">
        <annotations>
            <description>Fill the field in the Inline Translation form by provided text on Storefront.</description>
        </annotations>
        <arguments>
            <argument name="translateText" type="string" defaultValue="Translated"/>
        </arguments>

        <clearField selector="{{InlineTranslationModeSection.inputCustomTranslate}}" stepKey="clearCustomTranslateField"/>
        <fillField selector="{{InlineTranslationModeSection.inputCustomTranslate}}" userInput="{{translateText}}" stepKey="fillCustomTranslateField"/>
    </actionGroup>
</actionGroups>