Hello Gwenn,
I followed the tutorial you linked and almost everything worked fine for me. I did run into an issue where the floor in the map that was loaded was missing, although everything else was present, along with the modified shooting. I believe that’s due to not including Engine Content, while this floor is from Engine Content.
Would it be possible for you to add a level, even if it’s blank, to your plugin and then try the process you’re using? Once you launch the game, try opening the map using the console as shown in the tutorial and see if that will at least work for you so we can try to narrow down what’s occurring.
As far as checking to see if a specific plugin is loaded, I’m not sure but it doesn’t seem like it would be possible. In the modding process, we’re only taking the .pak file itself and adding the content to the project manually.