"I have no energy."
Translation:Jag har ingen energi.
I'd say no. When you say that you don't orka, it's always something specific that you don't have the energy for, while if you say that you don't have any energy, it just means that you're tired.
We pretty much have to accept it, considering we accept a huge range of different translations into English for orkar :) But I agree with you, I think this could be Jag orkar inget but Jag orkar inte ought to be I don't have the energy.
You also accept "jag orkar ej", btw, which surprised me. I had typed "jag orkar" and adding "ej" was the suggested fix, even though you don't seem to accept "ej" for "inte" anywhere else.
Nah, we try to accept ej for inte everywhere. There may still be places where we've missed it of course but I'm sure they are a small minority among our sentences. I don't know why it suggests ej first since inte is first in the bracket, but I guess you can't trust Duo completely.