hi CEC_2013
Don't too much worry comparing the marks against IELTS, both exams has it's own format. We can say IELTS 6 = 4L in CELPIP, but it is just a rough idea. In both exams they are testing our English proficiency and the marks are just the standard for the measurement. So we need to improve our English and if we are good in that we will get the required marks. If you go like I need to answer these many questions to pass, we are worrying about only answering questions not about our English proficiency which I would say not good and may give bad result. So don't too much worry about how they calculate mark etc. but concentrate on English improvement then we will get what we need.
Also I would suggest to you to buy their online training course (if you buy while registering you will get some discount) there we can try the real format of exam multiple time - so we will get a practice too..
I didn't get a chance to check with them about marks, when I get time I will check and let you know..
all the best.