I may have massively misunderstood some translations, but why isn't it: kjempeinteressant
I looked kjempeinteressant up on google translate and it said that it meant "fight interesting". Is it supposed to be very interesting?
Yes. Google Translate is highly entertaining, but not very reliable.
"Å kjempe" means to fight, so that's where the error comes from.
As there should be.
Sometimes we like to pretend we're a little more refined than we really are. ;)