Steps to reproduce the issue

Create a child template of Cassiopeia.
Add file tpl_cassiopeia_mytemplate.ini containing the following line:
TPL_CASSIOPEIA_XML_DESCRIPTION="My Cassiopeia child template."
Create / edit a child template style.

Expected result

TPL_CASSIOPEIA_XML_DESCRIPTION uses the child template text.
All other language constants use the Cassiopeia text.

Actual result

TPL_CASSIOPEIA_XML_DESCRIPTION displayed as expected.
All other language constants displayed without translation.

System information (as much as possible)

PHP 8.2

Additional comments

Suggested fix
File: com_templates/src/Model/StyleModel.php
Replace lines 399-402 with...

// Default to using parent template language constants
$lang->load('tpl_' . $data->parent, $client->path)
|| $lang->load('tpl_' . $data->parent, $client->path . '/templates/' . $data->parent);
// Optional overrides for child template language constants
$lang->load('tpl_' . $template, $client->path)
|| $lang->load('tpl_' . $template, $client->path . '/templates/' . $template);