Find the default site's entry by path, then find the entry for the current site/language and return that entry's url

Extension.php

<?php

/** Find primary site's entry by path and return translated variant */
public function getEntryByDefaultPath($defaultPath)
{
  $primaryHandle = Craft::$app->getSites()->getPrimarySite()->handle;

  $currentHandle = Craft::$app->getSites()->getCurrentSite()->handle;

  $primaryEntry = \craft\elements\Entry::find()->site($primaryHandle)->uri($defaultPath)->one();

  if ($currentHandle == $primaryHandle) return $primaryEntry;

  return $primaryEntry ? \craft\elements\Entry::find()->id($primaryEntry->id)->site($currentHandle)->one() : null;
}

macro.twig

{# This macro finds the default site's entry by path, then finds the entry for the current site/language and returns the correct url,
   It solves an issue with translated paths. {{ siteUrl('account/orders') }} would result in '/de/account/orders' instead.

Example:
  {% from '_macros/parts' import siteUrlByDefaultPath %}
  <a href="{{ siteUrlByDefaultPath('account/orders') }}">{{ 'Orders'|t }}</a>
  This would result for a German site in: <a href="/de/konto/bestellungen">Bestellungen</a>
  The twig function {{ siteUrl('account/orders') }} would have erroneously resulted in '/de/account/orders'
#}
{% macro siteUrlByDefaultPath(defaultPath) %}
  {% if currentSite.handle == craft.app.sites.primarySite.handle %}
    {{ url(defaultPath) }}
  {% else %}
    {% set foundEntry = craft.entries.site(craft.app.sites.primarySite.handle).uri(defaultPath).one() %}
    {% set currentSiteEntry = foundEntry ? craft.entries.id(foundEntry.id).site(currentSite.handle).one() : null %}
    {{ currentSiteEntry ? currentSiteEntry.url : url(defaultPath) }}
  {% endif %}
{% endmacro %}