Why weren't they failed for the language task
 

They only showed Cameron and Zoe. The results must have been really terrible and made for bad TV.
Machinegun-mouth Lewis deserved a failure for sitting stock-still like a spoiled brat when all the others were faking turbulence.

I think BB decides the task results before the shopping tasks even begin.

That's obvious ! .
They definitely failed the Chinese Language test . BB was too nice to them , in the old classic BB they would of only been allowed a maximum of 5 fails ! .