When I first saw the sentence …
Oui, et on va voir que ce n'est pas si terrible que ça et que quelquefois, c'est même amusant !
… I wondered what the que ça was for. Then I learned that que ça can mean as that, so that the sentence makes more sense as, … not so terrible as that … or … not as terrible as that … , which would not be uncommon in English, especially if the sentence ended there. Then I found that pas si [adjective] que ça is an expression meaning, not so [adjective]. So, the question is, is pas si [adjective] que ça a fixed phrase expression that shouldn't be broken up, or is the que ça optional, as in English.