The plugin uses the path defined in Timber::$locations as the templates path or falls back to the uploads folder if none is provided.
Either adjust your Timber::render('page.twig', $context)-functions like this:
$filenames = [TimberEditor::getTemplateFilename(), 'page.twig'];
Timber::render($filenames, $context);
like this
TimberEditor::render('page.twig', $context);
# 'page.twig' serves as a fallback if the current posts's template doesn't exist
or like this
TimberEditor::renderPost('page.twig', $context);
# renderPost() automatically adds ['post' => new Timber\Post()] to the $context