Standard rock names are often either too general or too specific but the vocabulary still needs to be broadly compatible with geological descriptions, and mixed materials are challenging.

Yes, its tricky to come up with a good schema for parent materials that highlights the important details. I think recording mode of deposition, parent rocks (weathering sources), and mineralogy (weathering products) separately helps. The 'parent rocks' list is the hardest to formulate well...

What's this particular loess made of?

The USDA system separates the two concepts relatively well, so you may not have encountered this.

because the residual-soil terms carry information about material's mineralogical composition but the transported-soil terms don't. So when I see a term like loess, I get a lot of info about grain size distribution and I can make inferences about permeability and structure etc from that but also:

A thing that I've noticed in some soil description systems (e.g. WRB) is that a 'parent materials' list is supplied but that it lists rock names for residual soils and then switches to particle size and mode of deposition for anything transported. Putting these two concepts in one list is wrong imo,

Now I get to air my pet peeve about how terms for particle size and mode of deposition aren't lithologies!

All roads lead to The Arena.

Christ, it's even worse after getting into bed.