diff --git a/src/Core/L10n.php b/src/Core/L10n.php
index 1d8cfa705..636cb1190 100644
--- a/src/Core/L10n.php
+++ b/src/Core/L10n.php
@@ -378,7 +378,7 @@ class L10n
 	 *
 	 * @return array
 	 */
-	public static function getAvailableLanguages(): array
+	public function getAvailableLanguages(bool $additional = false): array
 	{
 		$langs              = [];
 		$strings_file_paths = glob('view/lang/*/strings.php');
@@ -392,10 +392,78 @@ class L10n
 				$path_array            = explode('/', $strings_file_path);
 				$langs[$path_array[2]] = self::LANG_NAMES[$path_array[2]] ?? $path_array[2];
 			}
+
+			if ($additional) {
+				// See https://github.com/friendica/friendica/issues/10511
+				// Persian is manually added to language detection until a persian translation is provided for the interface, at
+				// which point it will be automatically available through `getAvailableLanguages()` and this should be removed.
+				// Additionally Portuguese, Ukrainian, traditional Chinese and Welsh are added to that list.
+				$additional_langs = [
+					'cy'      => 'Cymraeg',
+					'uk'      => 'Українська',
+					'pt-PT'   => 'Português',
+					'zh-hant' => '繁體',
+					'fa'      => 'فارسی'
+				];
+				$langs = array_merge($additional_langs, $langs);
+				ksort($langs);
+			}
 		}
 		return $langs;
 	}
 
+	/**
+	 * The language detection routine uses some slightly different language codes.
+	 * This function changes the language array accordingly.
+	 *
+	 * @param array $languages
+	 * @return array
+	 */
+	public function convertForLanguageDetection(array $languages): array
+	{
+		foreach ($languages as $key => $language) {
+			$newkey = $this->convertCodeForLanguageDetection($key);
+			if ($newkey != $key) {
+				if (!isset($languages[$newkey])) {
+					$languages[$newkey] = $language;
+				}
+				unset($languages[$key]);
+			}
+		}
+
+		ksort($languages);
+
+		return $languages;
+	}
+
+	/**
+	 * The language detection routine uses some slightly different language codes.
+	 * This function changes the language codes accordingly.
+	 *
+	 * @param string $language
+	 * @return string
+	 */
+	public function convertCodeForLanguageDetection(string $language): string
+	{
+		switch ($language) {
+			case 'da-dk':
+				return 'da';
+			case 'en-us':
+			case 'en-gb':
+				return 'en';
+			case 'fi-fi':
+				return 'fi';
+			case 'nb-no':
+				return 'nb';
+			case 'pt-br':
+				return 'pt-BR';
+			case 'zh-cn':
+				return 'zh-Hans';
+			default:
+				return $language;
+		}
+	}
+
 	/**
 	 * Translate days and months names.
 	 *
diff --git a/src/Model/Item.php b/src/Model/Item.php
index 1e16f85d9..e48bae77a 100644
--- a/src/Model/Item.php
+++ b/src/Model/Item.php
@@ -2015,11 +2015,8 @@ class Item
 
 		$naked_body = self::getDominantLanguage($naked_body);
 
-		$availableLanguages = DI::l10n()->getAvailableLanguages();
-		// See https://github.com/friendica/friendica/issues/10511
-		// Persian is manually added to language detection until a persian translation is provided for the interface, at
-		// which point it will be automatically available through `getAvailableLanguages()` and this should be removed.
-		$availableLanguages['fa'] = 'fa';
+		$availableLanguages = DI::l10n()->getAvailableLanguages(true);
+		$availableLanguages = DI::l10n()->convertForLanguageDetection($availableLanguages);
 
 		$ld = new Language(array_keys($availableLanguages));
 		return $ld->detect($naked_body)->limit(0, $count)->close() ?: [];
diff --git a/src/Model/User.php b/src/Model/User.php
index d6dfa3525..b4df99d82 100644
--- a/src/Model/User.php
+++ b/src/Model/User.php
@@ -536,22 +536,18 @@ class User
 /**
  * Fetch the language code from the given user. If the code is invalid, return the system language
  *
- * @param integer $uid   User-Id
- * @param boolean $short If true, return the short form g.g. "en", otherwise the long form e.g. "en-gb"
+ * @param integer $uid User-Id
  * @return string
  */
-	public static function getLanguageCode(int $uid, bool $short): string
+	public static function getLanguageCode(int $uid): string
 	{
 		$owner = self::getOwnerDataById($uid);
-		$languages = DI::l10n()->getAvailableLanguages();
+		$languages = DI::l10n()->getAvailableLanguages(true);
 		if (in_array($owner['language'], array_keys($languages))) {
 			$language = $owner['language'];
 		} else {
 			$language = DI::config()->get('system', 'language');
 		}
-		if ($short) {
-			return substr($language, 0, 2);
-		}
 		return $language;
 	}
 
diff --git a/src/Module/Conversation/Channel.php b/src/Module/Conversation/Channel.php
index dfe8871f1..eacbb2201 100644
--- a/src/Module/Conversation/Channel.php
+++ b/src/Module/Conversation/Channel.php
@@ -144,8 +144,8 @@ class Channel extends BaseModule
 				'accesskey' => 'h'
 			];
 
-			$language  = User::getLanguageCode($this->session->getLocalUserId(), false);
-			$languages = $this->l10n->getAvailableLanguages();
+			$language  = User::getLanguageCode($this->session->getLocalUserId());
+			$languages = $this->l10n->getAvailableLanguages(true);
 
 			$tabs[] = [
 				'label'     => $languages[$language],
@@ -344,7 +344,7 @@ class Channel extends BaseModule
 		} elseif (self::$content == self::AUDIO) {
 			$condition = ["`media-type` & ?", 4];
 		} elseif (self::$content == self::LANGUAGE) {
-			$condition = ["JSON_EXTRACT(JSON_KEYS(language), '$[0]') = ?", User::getLanguageCode($this->session->getLocalUserId(), true)];
+			$condition = ["JSON_EXTRACT(JSON_KEYS(language), '$[0]') = ?", $this->l10n->convertCodeForLanguageDetection(User::getLanguageCode($this->session->getLocalUserId()))];
 		}
 
 		if (self::$content != self::LANGUAGE) {
@@ -404,10 +404,11 @@ class Channel extends BaseModule
 	private function addLanguageCondition(array $condition): array
 	{
 		$conditions = [];
-		$languages  = $this->pConfig->get($this->session->getLocalUserId(), 'channel', 'languages', [User::getLanguageCode($this->session->getLocalUserId(), false)]);
+		$languages  = $this->pConfig->get($this->session->getLocalUserId(), 'channel', 'languages', [User::getLanguageCode($this->session->getLocalUserId())]);
+		$languages  = $this->l10n->convertForLanguageDetection($languages);
 		foreach ($languages as $language) {
 			$conditions[] = "JSON_EXTRACT(JSON_KEYS(language), '$[0]') = ?";
-			$condition[]  = substr($language, 0, 2);
+			$condition[]  = $language;
 		}
 		if (!empty($conditions)) {
 			$condition[0] .= " AND (`language` IS NULL OR " . implode(' OR ', $conditions) . ")";
diff --git a/src/Module/Settings/Display.php b/src/Module/Settings/Display.php
index b870c91ac..fa1496da6 100644
--- a/src/Module/Settings/Display.php
+++ b/src/Module/Settings/Display.php
@@ -218,8 +218,8 @@ class Display extends BaseSettings
 			BBCode::PREVIEW_LARGE    => $this->t('Large Image'),
 		];
 
-		$channel_languages = $this->pConfig->get($uid, 'channel', 'languages', [User::getLanguageCode($uid, false)]);
-		$languages         = $this->l10n->getAvailableLanguages();
+		$channel_languages = $this->pConfig->get($uid, 'channel', 'languages', [User::getLanguageCode($uid)]);
+		$languages         = $this->l10n->getAvailableLanguages(true);
 
 		$first_day_of_week = $this->pConfig->get($uid, 'calendar', 'first_day_of_week', 0);
 		$weekdays          = [