Is there some way to create sections inside static translations? (craft v3)
You can include custom translation categories within your config/app.php

return [
    'modules' =&gt; [
        'my-module' =&gt; \modules\Module::class,
    ],
    'components'    =&gt; [
        'i18n' =&gt; [
            'translations' =&gt; [
                'foo'  =&gt; [
                    'class'            =&gt; \craft\i18n\PhpMessageSource::class,
                    'forceTranslation' =&gt; true,
                    'basePath'         =&gt; '@translations',
                ],
            ]
        ]
    ]
    //'bootstrap' =&gt; ['my-module'],
];


This will include the custom group foo to your app, make sure to change the basePath variable to a path you like

That being said your folder structure will look like

-your base path
|-- en-US
|-----&gt; foo.php
|-- de-DE
|-----&gt; foo.php


within these files you can create your custom translations

return [
    'foo' =&gt; 'bar'
];


{{ 'foo'|t('foo') }} -&gt; will now display bar
{{ 'foo'|t('site') }} -&gt; will still show foo