Pull Request resolves #48759

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

Root Cause:

1. ModulesHelper::getTranslatedModulePosition() previously called Text::_($langKey) before checking if the language key existed, and relied on self::isTranslatedText() ($text !== $langKey) to trigger fallbacks. With Language Debug enabled, Text::_() wraps missing keys in ??...??, causing $text !== $langKey to evaluate to true and skip all fallbacks.
2. Neither ModulesHelper nor PositionsModel checked templateDetails.xml for a <parent> template, meaning child templates could not inherit position language keys from their parent template.

How this PR addresses the root cause:
1. ModulesHelper::getTranslatedModulePosition():

• Parses templateDetails.xml to detect if a template has a <parent> template, and loads the parent template's tpl_<parent>.sys.ini file.
• Checks $lang->hasKey() before calling Text::_() so missing keys do not show up as untranslated in the Language Debug logs.
• Adds a parent template translation fallback (Child Template $\rightarrow$ Parent Template $\rightarrow$ com_modules $\rightarrow$ humanized position name) and strips the parent template prefix when humanizing position names.

2. ModulesHelper::isTranslatedText():

• Explicitly checks $text !== '??' . $langKey . '??' so strings wrapped by Language Debug are properly recognized as untranslated.

3.PositionsModel::getItems():

• Loads tpl_.sys.ini when is present in templateDetails.xml and falls back to TPL_POSITION* before COM_MODULES_POSITION_*

Testing Instructions

0. Go into Global Configuration and enable Debug Language in the System tab.
1. Go to System $\rightarrow$ Site Templates $\rightarrow$ Styles.
2. Find Cassiopeia Extended - Default.
3. If its star in the Default column is not selected, click it. The selected star marks the default site template style.
4. Go to content $\rightarrow$ site modules and select a module
5. Select the positions dropdown

Actual result BEFORE applying this Pull Request

Untranslated strings.

Expected result AFTER applying this Pull Request

Strings are appropriately translated.

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed