Louis,
Like the Coltrane story. I am also happy to know that I am not the only one who has difficulty in creating a picture from the words.
I should note that Yang Jun, Yang Zhenji and Fu.... are my authorities. My interest in the older methods of YCF, Yang Sau chung, Yang Shou Hou, and Yang Ban Hou is probably in terms of history and development the same as yours and Audi's interest in language. The evolution of language is of great interest to me though I have few skills myself in it.
Recently i have stopped practicing the Kwan Ping Yang style. It has been described as coming from Ban Hou. Parts of it are obviously from an older Yang style (maybe all of it) and the moves or positions (or "forms") are often very similiar to our style but have different names and intent as far as technique. Then again they may share the same name but bear no other similarity.
I have found that these different techniques/intent have helped me understand much much more about the potential of our "set" especially in transitions. I see much more hidden there, much of which I fear might becoming lost over the years of change. Little differences in performance among the various Yang lines have meaning. They may reflect personal preferences technique wise that may vary between A Yang Shou Hou and a Yang Cheng Fu or YAng Sau Chung and YAng Zhen Duo....or maybe even philosphical differences. I find that all enhance each the other and lend greater depth to my understanding of the set that I have inherited from Yang Zhen Duo and Yang Jun.
As we spoke of before, Single Whip can be practiced with different intent at different places in the set. And again, outside of form practice I can practice the various techniques themselves with a partner. So when I read about the Single Whip discussed by YCF in your translation or that article I grab onto it as something to be understood and treasured. And like you said, the words may be lacking the details of precise movement but much can be pieced together from these "hints" and the manner that the Fu or Dong families,..., may do things. And with this, though somewhat subjective, one can get a broader scope of the history and development of Yang Taiji. And you are more than correct about the older manuals as putting us "...in closer touch to the source." That probably is their greatest value. There are "treasures" to be gleaned from them.
Very important to me, though I embrace change, is to lose as little as possible of the "old" at the same time. So many say that they have the "authentic" "original" Yang Lu Chan taiji. This tells me that it probably has been lost for good in it's entirety, only bits and pieces probably remain in the various Yang lines and some elsewhere. This is a very sad loss. It is inevitable just as we lose species daily from the planet....it is always an unfortunate thing---though if Ticks would vanish I would not cry. Ha!
I really have no expectations from manuals or even teachers. AS Michelangelos motto says "Ancora Imparo" (My modern Italian friend says there should be an O instead of an A in Ancora) "I am still learning." and each little shred of info like that from YCF on when he formed the hook at that place in time tells me something more even if I don't have the full picture yet. Questions are good. The questions often are the answers in themselves.
Now if I could read Chinese or those more knowledable than me would translate more of the older and the modern Chinese manuals like the YCF or YZJ or.....just giving you the business. I always appreciate and learn from your translations and ideas, and am more than thankful.
My best,
Michael