Does the Catholic Church endorse the children of narcissistic parents breaking off contact with them (not necessarily permanently/forever)?

I'll try to answer this by making reference to the Catechism of the Catholic Church, but it may not be the cut-and-dried answer you want. Ken's comments are a good summary of the stance of the Church: that it is up to individual conscience.

Here's what the catechism says about the fourth commandment:

2216 Filial respect is shown by true docility and obedience. "My son, keep your father's commandment, and forsake not your mother's teaching.... When you walk, they will lead you; when you lie down, they will watch over you; and when you awake, they will talk with you."20 "A wise son hears his father's instruction, but a scoffer does not listen to rebuke."21

2217 As long as a child lives at home with his parents, the child should obey his parents in all that they ask of him when it is for his good or that of the family. "Children, obey your parents in everything, for this pleases the Lord."22 Children should also obey the reasonable directions of their teachers and all to whom their parents have entrusted them. But if a child is convinced in conscience that it would be morally wrong to obey a particular order, he must not do so. As they grow up, children should continue to respect their parents. They should anticipate their wishes, willingly seek their advice, and accept their just admonitions. Obedience toward parents ceases with the emancipation of the children; not so respect, which is always owed to them. This respect has its roots in the fear of God, one of the gifts of the Holy Spirit.

So there are a few things to note here which can guide us. First is that a child in his father's home must obey every just command. This means that the children of narcissistic parents who lives at home need not obey unjust commands from his parents, such as those commands to indulge the parent's vain and sinful behavior. But if the father says to, for instance, clean up the kitchen, that is a normal filial duty a child might have (assuming it is age appropriate), and thus the child must obey even if the parent gives the order for a vain reason. That is my understanding of the passage.

Furthermore, adult sons and daughters who no longer live at home owe their parents respect, but what that respect looks like can be hard to discern, and will depend on the specific circumstance. Certainly, it is not respectful to affirm a parent in their sin or indulge their vices. So a child of narcissists may need to abstain from behaviors that affirm to their parents their vicious behavior. Things like indulging the parent's ridiculous whims or playing along with manipulative games, allowing oneself to be manipulated, seems almost to be positively disrespectful. Such behavior is rooted in an assumption that the parent is either not responsible for their vicious behavior or is unable to change. More than being just disrespectful, this attitude is an implicit denial of the efficaciousness of God's Grace to heal sinners.

Given this, although there appears to be no hard and fast rule from the Church, I would argue that there are certainly instances when a faithful Catholic can and even should break contact with a parent. Most notably: when that breach of contact is intended to induce the parent to repent of sin.

Disclaimer: I personally have had to do this in my own life. My father refuses to repent for the real and grave sins he has committed against me and my mother and I have made it clear to him that I want to have a relationship with him, but I need a real apology first where he names the things he's done to hurt me and apologizes, not just vaguely apologizing for "the hurt he's caused" generally, which is all he's willing to do. Through prayer and conversation with my wife, I'm convinced that this is honestly best for everyone involved. It will, hopefully, make him think about his behaviors and repent, and it also will protect our future children from harm (without going into detail, he can be very manipulative and is also an anti-Catholic non-denominational Christian, so we have concerns about him undermining our beliefs to them as well).

I think I honestly struggle the most with this commandment because my father is not the kind of man I could respect if he was just some guy I met on the street and I knew everything he had done to his family, but I am still obliged to dig deep and find some way to respect him in spite of that, according to my Church and my faith.

Conclusion: I think that the catechism is the best guide on this. It spells out the expectation for filial obedience, where that ends, and the fact that respect is still owed to parents very clearly. What we need to keep most in mind for this question, though, is that cutting contact is not in itself disrespectful, and can even be medicinal for the parent who has strayed from the straight and narrow way, and hence would be in those cases the most respectful thing a child could do.