The code in question is around Carbonite.Quest\NxQuest.lua:8777 - we would have to find those cTypes that are measured in Gold - here's a list (probably incomplete):
http://wow.gamepedia.com/API_GetAchievementCriteriaInfo
After finding out our criteria is measured in Gold, we'll have to alternate our formatting of the Achievement goal.
It's a nice feature, so I'll have a look into it.
Update: I tested it and it works great so far, so I have pushed it to github - expect to see it in the next version (at least for achievements).