She's speaking Khmer. It's officially the language of Cambodia, but you find it in a lot of the other rougher corners around Vietnam, Thailand, Laos and Myanmar, including the Golden Triangle. Khmer gangs control much of the drug- and people- smuggling (and loansharking, illegal gambling, prostitution, etc) happening in that part of the world.
As always, Susan writes herself; the Khmer snippets are mostly her threatening and insulting the gang boss she's talking to.