I do not think Real Madrid will have easy time in Champions League with their current team. They have history of doing well in tournament but last year they got lucky because of mistakes made by other teams. They also won some games at very last minute. Other teams like Bayern Munich could have won if they made different decisions. This means Real Madrid did not just win because they were best but also because of things outside of their control. So I think they will face problems in Champions League with their current team.
I will even say that Bayern could have won if the referees had made different decisions, but that is no longer important. I agree with you that Real Madrid was very lucky in several matches of the Champions League. It is obvious that they have more problems now and this is already reflected in their results in La Liga, I think that in the Champions League they will be even more obvious because the opponents there are also stronger. But perhaps this will be more obvious at later stages of the tournament.
One thing you should understand is that Real Madrid is more focused in UCL than in Laliga. Their poor performance in Laliga currently does not mean that if they are playing in the champions league that they will not perform well. Ypu should remember that group stage is always not difficult for them to qualify.
What i only see as a challenge for them currently is the number of their injured players that might not recover quick but i think Ancelotti will take care of it