While I understand where people have gotten this idea but unfortunately it is far from fact. Just because a lot of people say something and I realize there are numerous people on this website (which I love and recommend to everyone) take this point of view, doesn’t make it right. You can ask any liturgist and they will tell you that you are mistaken. To say that the readings don’t matter when it comes to a Mass fulfilling your weekend obligation is like saying you can come into Mass at the Creed and it qualifies as attending Mass, it doesn’t wash. A valid Mass is all three parts together, the Penitential Rite, the Liturgy of the Word and the Liturgy of the Eucharist. If you miss out on 2/3, well then, you have missed it. You can’t just show up for communion and then leave and say you attended Mass. The Church has set certain readings aside for certain Sundays for a reason, she wants you to receive a specific message on those weekends. Unless the appropriate readings are used for weekend funerals, weddings, and, yes, even Confirmation, then the Church does not consider it the obligatory Mass.
This has only been an issue over the past few decades. When I was growing up, it was never a question, we just knew. There was one Mass with certain readings, that fulfilled your Sunday obligation and all others didn’t. Vatican II didn’t change that. One also can’t take Canon 1248 out of CONTEXT. It has to be read with the GIRM, the Rubrics and the Sacramentary. This is really something that only a priest or bishop should determine, preferably the Office of Divine Worship at the USCCB. We warn people not to take Bible verses out of context, Canon Law, Encyclicals, etc… should be read in the same way.
As far as celebrating All Soul’s day on the weekend and having it fulfill one’s obligation, in the United States the Bishops allow for the celebration of the memorial. They also allow for other feast days to be optional on weekends such as Our Lady of Guadelupe, etc…but they usually have to fall within the 2 days of the weekend. When it comes right down to it, it is ultimately the decision of the bishops and then the priests. In both of these cases, questions should be referred to the individual pastors because there may not be one blanket answer and we can’t have all the facts for each incident.