RESOLVED
The line trace did not work because it conflicted with the script to show the mouse. Unfortunately for me, I only realized it after migrating the project, building the lights, etc… 5 hours of work later.
No door system was needed, as you advised me, I set up an interface and added a simplified collision box on each element I want to interact with. Now I can open them autonomously on click, as I wanted.
Thanks so much again for the help!
Here are the links of the tutorials I followed, if someone after me should have my problem 