The book of Jubilees was a novel work of non-scriptural, non-prophetic literature that was composed about 100 years before the destruction of the Second Temple. Whatever it's author might have suggested, no matter how well-intentioned, does not override or impact on any point of Mosaic law. The relevant foundational principle is that a Gentile is not allowed to create a new (i.e. a man-made) religion or any new commandments.
From The Divine Code, 4th Edition, by Rabbi Moshe Weiner, Part I, topics 3:2,3 -
"if a Gentile abstains from weekday activities and makes a sabbath for himself, even on a weekday, he is liable [for making a new religion or adding a new commandment]. This obviously includes one who establishes a 'holy day' for himself that is similar to the holy days and Sabbaths of the Jews (which are religious holidays, i.e. 'holy convocation' days), during which he prohibits himself from work, since this is creating for himself a new religion. Not only is taking on a sabbath day forbidden, but even the setting aside of any day for a specific religious observance or statute, such as one who establishes for himself a time to eat a special food as a precept (e.g., eating unleavened bread on Passover), or to fast on a specific day (e.g., the Jewish fast day of Yom Kippur), and the like. Even if he did not also set it aside as a sabbath or festival day (i.e., for refraining from work), this is considered as creating a festival and a religion from his own comprehension. However, if he sets up for himself a day of rest from work, not as a holiday but just as a break from work, it is permissible, for he is not establishing it as a religious precept from his own comprehension... But if a Gentile wants to eat unleavened bread or sit in a sukkah booth for his physical pleasure (e.g., if he likes eating unleavened bread, or sitting in a sukkah booth for shade from the sun's heat), he is allowed to. This is so even during the Jewish festival days, since he does not intend at all to observe the Jewish commandment, but he does the action only for his own physical satisfaction, and he is not establishing a festival for himself..."
Participating in annual secular activities and commemorating historical events (for example, a national independence day), even if they involve a festive meal, are certainly permissible.
From The Divine Code, 4th Edition, by Rabbi Moshe Weiner, Part I, topics 3:2,3 -
"if a Gentile abstains from weekday activities and makes a sabbath for himself, even on a weekday, he is liable [for making a new religion or adding a new commandment]. This obviously includes one who establishes a 'holy day' for himself that is similar to the holy days and Sabbaths of the Jews (which are religious holidays, i.e. 'holy convocation' days), during which he prohibits himself from work, since this is creating for himself a new religion. Not only is taking on a sabbath day forbidden, but even the setting aside of any day for a specific religious observance or statute, such as one who establishes for himself a time to eat a special food as a precept (e.g., eating unleavened bread on Passover), or to fast on a specific day (e.g., the Jewish fast day of Yom Kippur), and the like. Even if he did not also set it aside as a sabbath or festival day (i.e., for refraining from work), this is considered as creating a festival and a religion from his own comprehension. However, if he sets up for himself a day of rest from work, not as a holiday but just as a break from work, it is permissible, for he is not establishing it as a religious precept from his own comprehension... But if a Gentile wants to eat unleavened bread or sit in a sukkah booth for his physical pleasure (e.g., if he likes eating unleavened bread, or sitting in a sukkah booth for shade from the sun's heat), he is allowed to. This is so even during the Jewish festival days, since he does not intend at all to observe the Jewish commandment, but he does the action only for his own physical satisfaction, and he is not establishing a festival for himself..."
Participating in annual secular activities and commemorating historical events (for example, a national independence day), even if they involve a festive meal, are certainly permissible.