Yellow is still a non-canonical colour in the church. Blue is also non-canonical.
The five canonical colours are (1) white used at Easter, Christmas, Circumcision, and Epiphany; (2) red at Exaltation and Invention of Cross, Pentecost, and Feasts of Martyrs; (3) violet on Ash Wednesday, Lent, Septuagesima, Quinquagesima, and Advent; (4) black on Good Friday; (5) green on ordinary Sundays and week days.