You’re probably about to scratch your head. Yes and no. Yes, in that it is essential to believe the Holy Spirit proceeds from the Father and the Son “not as from two principles, but as from one principle; not by two spirations, but by one single spiration” (Second Council of Lyons, 1:1). No, in that the expression of the phrase itself is not necessary.
It should be noted that the Eastern Catholic Churches do not include the Filioque clause in the Nicene Creed and never have. The Filioque clause was added in the 5th century, two centuries after the Nicene Creed was written; this was done in the Latin Church in which the Latin Fathers developed a theology of the Holy Spirit proceeding from the Father and the Son. In the Eastern Churches the Eastern Fathers taught the Holy Spirit proceeds from the Father through the Son.
Saint Maximus the Confessor defended the Filioque by saying the Latins “have shown that they have not made the Son the cause of the Spirit — they know in fact that the Father is the only cause of the Son and the Spirit, the one by begetting and the other by procession” cf. Letter to Marinus). The Catechism as such states that the Father is “principle without principle” (n. 248). So, essentially the East and West agree that the Father is the “first origin of the Spirit” (ibid.) and that the Father proceeds from the Father through the Son. In sense the Spirit proceeds from the Son since He proceeds through the Son whom is shown to have power over Him to send Him to the Church (rf. John 15:26).
The United States Conference of Catholic Bishops wrote an article stating that “the Latin and Greek traditions … differed in their ways of describing the relationship among the persons of the Trinity.”
So essentially both the East and West do confess that the Father is “the first principle” of the Holy Spirit as Saint Augustine said (rf. CCC 264), just differently.