ALT =LET(
_an,SEQUENCE(10,1,0),
_kn,TEXT(_an,"[DBNum1]0"),
_split,MID($B$2,SEQUENCE(11),1),
_astr,CONCAT(IFNA(INDEX(_an,MATCH(_split,_kn,0)),_split)),
_serial,_astr XLOOKUP(A3,{"翌日","翌々日","翌週","昨日","一昨日","先週"},{1,2,7,-1,-2,-7},0),
TEXT(_serial,"[DBNum1]yyyy年m月d日")
)