Leaving in Japanese words whent the meaning can be conveyed by english equivalents is not good translation. Okaasan means 'mother' there is absolutely no reason to leave it untranslated.
"I'm going to the festival with mother tonight!" Sounds natural, but "Teacher will also be coming too...
It's like in cartoons when a character runs off a cliff and gravity takes a while to kick in.
And it's camouflage. Despite us being alone in the middle of the woods...