Translation:When I am hungry, I always am discontented.
Would another synonym of malkontenta be upset, or is there a specific word for that in Esperanto?
I think "dissatisfied" may be one however "upset" seems to convey more than just not being content. Upset is more like maltrankviligxa
Why is "discontent" wrong? Why does it have to be "discontented"?
Yes, "discontent" seems better.
"Discontent" is not correct here because it is a noun, e.g. 'there was growing discontent among the workers". "Discontented" is correct here because it is an adjective describing the person's feelings. However, it is an awkward choice of word. I used "unhappy" when doing this exercise, and this was accepted.
"Discontent" is also an adjective, personally it sounds more natural than discontented in this case.
Discontent is an adjective as well as a noun. It us however used far more often in English as an adjective.
Did you mean "Mi malŝatas esti malsata"? ("I don't like being hungry").
What does "hangry" mean? A typo for "hungry" perhaps? But then what's the point of writing two Esperanto words and an English one. Sorry if I'm being slow, but I just don't get what you mean.
Because "sad" in Esperanto is "malfeliĉa". "Malkontenta" means discontent or discontented, both of which, incidentally, can be adjectives according to the English dictionaries I have looked at. (The email I received notifying me of your post said that your message was "discontent is a noun, discontented is an adjective". You must have changed it.) Also, for "whenever", Esperanto uses "kiam ajn" - "kiam" by itself just means "when".