> Scalars, when applied to a specific curve, do have a “order” though,

Nitpick: the important point here is that points on the elliptic curve have order (by definition the smallest k such that kP = identity), and the group of such points has order (by definition, the number of elements it has). Here, scalar is just a way to say "not a point", or "integer value" and if you define them in the right group, sure, we could talk about their order as well, but what we actually care about is the order of the points.

From the definition of order, qP = identity, thus (q+30)P = qP + 30P = identity + 30P = 30P, hence the wrapping.