Hi, BLN, before I forget, look at the European section pallie, you will find climatically related friends there.
To your problem, it can be of 2 causes:
Too much dry heat, in which case the spots would represent a certain plant tissue damage to the leaves (not deadly) or it's just small cuttings from various insects and birds.
None of those conditions is deadly, sometimes the leaves do it, because the Trachys are from China region, where the humidity is higher than in Europe.