Regarding Madrid's match against Salzburg, we don't need to worry because Madrid will win easily to get full points in the match. Although some defenders are injured, we all know that the current substitute players are also very qualified and can also be relied on. On the one hand, Mbappe has begun to have great confidence to continue to contribute well to help Madrid provide great opportunities in the UCL. And for concerns about injured players, it seems that Ancelotti will not remain silent seeing the current squad conditions and we can just see the surprise that Ancelotti will give by bringing in new players with very good quality.
Its easy to believe Madrid is going to win this particular fixture without having to really stress, because looking at both squad they have so much differences and variations in their depth, strength and even in their tactical approach to games, and by all of this measure ls, Madrid appears to be ahead as Salzburg has got a weak defence good enough to pose some resistive strength at Madrid in this game, nevertheless Madrid will still needed to earn a victory here as Salzburg may not want to give it easily or make it easy for them actually.
Real Madrid will have to take this game serious, because they need these 3 points more than we can say, because if Real Madrid didn’t win the two last games, then I don’t think they will be among the teams that will be present in the round of 16 this season, which means they have no hope anymore. Although they have the highest chance of winning the game against Salzburg, it is a home game for Real Madrid, so it will be like a sure win for Real Madrid with no stress. Moreover, as you mentioned, Real Madrid is better than them in terms of strength and many other aspects.