Thanks for posting that, Chris.
I had imagined that the Hardie stuff was probably a Wall Accessory item. It is odd that the web site you show says suitable for v12, 13 and 14 only ... as wall accessories are not version dependent. It should work just fine in 15 and 16. You just have to download the Wall Accessories 'goodie' (Help > Download...), restart AC and add the Hardie library to your loaded libraries.
The reason the Accessories (and other Goodies) are available but not officially supported is that GS doesn't offer any technical support/help for them and keeps them around for user benefit, but without having resources to invest in improving them. E.g., the Accessory functionality hasn't changed in many years.
Because Accessories are an older technology, they do NOT support any but ordinary vertical walls - solid or composite. You cannot apply a wall accessory to a profiled wall, for example. (I assume you can't apply to a canted or battered wall either, but never tried.)
The cool part, as you saw, is that accessory objects are dynamically associated with walls (or roofs/etc) - and so are aware of window/door openings.
There are other limitations - partly the Accessory technology and partly the objects themselves. If programmed badly, the siding won't be properly aware of changes in the exterior trim of your windows/doors. The siding base may not be adjustable vertically - e.g., if you want a partial board at your deck. The siding will not be aware of corner boards (Hardie or otherwise) unless the object has a parameter to generate corner boards. The corners will join in a mitered way which is not how Hardie siding works - cannot be cut at a miter - but perhaps the library includes a corner cap. The ends - as in the video - will just hang in space with no corner board unless there is a parameter or you place one and do a solid element subtract. Etc.
The email and phone contact that you complained about - saying that this is Graphisoft's fault that things aren't up to date - is a generic contact for questions about ArchiCAD - not questions about the Hardie content. It appears from the video that the collaboration was with Graphisoft Australia (a reseller and developer of local Australian content), not Graphisoft HQ. Who knows. In any case, if GS helped, it is Hardie / Accel who is the distributor / supporter of the content... GS just offers the enabling Accessories add-on for use.
Using Accessories can cause no harm to your project. No fears. Things will either work well enough for you, or not, in which case you can just remove the add-on and content.
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB