These "other days" are not the Old Testament Feasts instituted for Israel by God in His Word. These "other days" are Romish festivals instituted for Romanists by the Deformed Church only millenia later. As the 1542-1621 Cardinal Archbishop Bellarmine of Capua stated in his own Catechism anent the 'Third[!] Commandment': "Remember the festivals, to keep them holy."
Thereby, the Christian Sabbath of Holy Scripture was ignored. Matt. 28:1; Mark 16:2,9; Luke 53:56 to 24:6; John 20:1,19,26; Acts 2:1; 20:67; I Cor. 16:1-2; Heb. 4:8-11 cf. 10:25; Rev. 1:10. Thereby, the Lord's day was, and is, degraded to the level of the saints' days appointed by Mediaeval Romanism. Thereby, Jesus Christ the only-begotten Son of God the Father was, and is, rather is demoted to the standing of mere mortals like "St." Teresa!