You can try using Date Increment() , but you might have to modify your month value (it seems to be character in your case, so use Num() to convert it in a formula).
Names Default To Here(1);
dt = New Table("TEST (4)",
Add Rows(1),
Compress File When Saved(1),
New Column("time", Numeric, Continuous, Set Values([4]), ),
New Column("date", Numeric, "Continuous", Format("d/m/y", 12), Input Format("d/m/y"), Set Values([3797452800]), )
);
dt << New Column("a", numeric, continuous, Format("d/m/y", 12), Formula(Date Increment(:date, "month", :time, "actual")));
It might also be important to check how your solution works in possible corner cases (Date Increment(31Jan2024, "month", 1, "actual"))
-Jarmo