"Missing template" when omitting file extensions (.html.twig) or underscore in PhpStorm

Question

(Copy of https://craftcms.stackexchange.com/q/39067/11582)

In this project where I'm using CraftCMS I'd like to be able to only have to refer to a twig file by it's name, just like it works in JS (e.g. import './js/scripts') and SCSS (e.g. @import './variables'), without the need for file extensions or underscores.

Background info: CraftCMS uses Yii2.

However, when I try that in Twig, then first of all CraftCMS doesn't like me omitting the "_" when the file starts with one (and the IDE for that matter), and when I omit the file extension, then PhpStorm simply doesn't like it, but CraftCMS can work with it. For everything to look and work smoothly, I need to write the file name as is.

I don't know whether this is an issue with how CraftCMS configures Twig, or PhpStorm itself.

I'm currently on PhpStorm 2021.3.2 and following are my Symfony and Twig settings

Did I forget to change something, or is that just how it is right now?

EDIT:

https://symfony2-plugin.espend.de/languages/twig/index.html

https://github.com/Haehnchen/idea-php-symfony2-plugin/issues/1770