Answer
At that point (IFS 10 Update 7), Conditional Fields weren't implemented in Aurena at all — configuring them in IEE has no effect on the same page's behavior in Aurena, and there was no separate Aurena-native way to configure this same filtered-dropdown behavior. If dependent/filtered dropdown behavior in Aurena is a requirement, check current release notes for whether Conditional Field support (or an equivalent Aurena-native mechanism) has since been added, since this reflects a specific historical release rather than a permanent architectural limitation.