I commented on this from the beginning somewhere in the translation
editor. I also put some thinking on this from the beginning and here is
the resulted.
Yes, you’re right by analogy, "Lanterna" is a feminine word.
However, here we are referring to the program Lantern. You do not say “a programa in Português”, you say “o programa”.
You do not say in Portuguese, “a software”. You say “o software”.
So if you are referring to the program Lantern, in Portuguese, O programa, then it is "o Lanterna", "O programa Lanterna".
Now, if you are there in the wideness and it is night and you ask someone to pick up a real Lantern for you, then you would say;
Por favor, vá até aquela tenda e pegue a lanterna que esta dentro da minha mochila.
Please, go to that tent and pickup a lanterna that is inside of my backpack.
Is that makes sense to you? Please, let me know?
Eduardo