On page 62 of the Codex, the armory description of Stormshard Mortar says it is barrage, as does the reference chart at the back of my book, as does page 22 of the White Dwarf which discusses the Wyvern. Are the English language books printed in NA printed at the same place as for Europe and Australia/NZ?
Yup. British spellings any everything. And I just looked, the Stormshard Mortar is barrage in the physical book.