Hi Jim - i've actually written many of the manuals on cocoa fermentation, and while i may or may not be familiar with the specific one you're referencing, i will say that - generally speaking - the ministry of agriculture and rural development in Vietnam simply doesn't possess the technical acumen or depth of expertise when it comes to cocoa processing. They're improving, and i've worked there for many years to help them along. but they're not there yet.
generally speaking, small fermentations are not consistent or repeatable. They are difficult to scale. yes, i know people do it - but that does not mean they do so repeatably nor consistently. in almost every instance where someone swears they have a small repeatable and consistent fermentation, they have no frame of reference against which to compare a truly consistent and repeatable fermentation against (i.e. they *think* it works because it's the only thing they know). and heck, perhaps it actually does work for whatever local use they're pursuing - i've seen instances where repeatability and consistently simply don't matter for local usage.
In Hawaii, Dole has a plantation (mike conway manages it), where smaller fermentations were developed under the assistance of Guittard. they ferment in wood containers a few hundred lbs at a time, with drainage, just under a week.
Recently there has been a bit of patent activity (and will be more to come) on micro fermentations (very small mass fermentations) that are consistent and repeatable, as there's huge scale advantage should that be successful. we're quickly closing those technical hurdles, but to date they require some laboratory equipment to facilitate them, and certainly aren't viable in the field.