The most settled long-term expats tend to reject the either-or framing entirely. You are not choosing between preserving your identity and adapting to the new country; you are slowly building a third thing that contains both. That reframe removes a lot of guilt in both directions.
Practically, traditions survive abroad when they get a fixed place on the calendar and other people involved. Celebrate your major festivals properly rather than approximately, cook the food that tastes like home, keep your language alive at home especially with children, and connect with the diaspora community for the celebrations that need a crowd. Cultural associations, places of worship, and community groups exist in most cities precisely for this.
At the same time, adopt local traditions genuinely rather than as an observer, because participating is what turns a posting into a life. Children benefit from seeing both cultures treated with pride rather than one as default and the other as homework. The balance will shift over the years; revisit it deliberately.