Either guide or game bug

In the guide you mention that you in the CL will meet your own league or 'very close to. However I am level 12 and meeting a level 13 in next round (first knockout stage) and he can assemble a 11 man squad with an average above 88 while the strongest we can buy using tokens in level 12 is 84. I would somehow claim that this has to be a bug because he is actually stronger than the strongest level 12 team can ever be.

Not a bug, I think what happened he boughts players from Mr. Scout, and/or power trained his players immediately upon season start. This is what makes it so challenging. A screenshot would be helpful, has he all 8* from your perspective? But really this is normal in the CL & Cup you can meet very strong opps.