Yes, the current winner always qualify in real life for the upcoming edition, and Europa League winner play the CL. So for realism the game stand with the real rules.
Then promoting 100%+ means that you'll face `1 levels in CL-Cup... by my viewpoint tanking isnt better than lower the AvQ to face equal and -1level teams... I won 19CLs and 15 SLs in many different situations, with +1L -1, tankers of different levels etc btw..