Why are British Commandoes penalised on SMGs?

Question: Page 25 of the Armies of Great Britain Book – It is +2pts to add a submachine gun to a Gurkha instead of the normal +3pts. I assume this is because Gurkhas already have Tough Fighters (included in their base cost) and so the redundant Tough Fighters bonus on the submachine gun has been discounted. This would make sense except that British Commandos who also have Tough Fighters (included in their base cost) still have to pay +3pts for submachine guns. This is I believe an unrecorded errata as Australian Commandos in the New Guinea book who are otherwise identical to British Commandos also are +2pts to add a submachine gun. How do I report this errata?