As long as you read the labeling carefully. For instance does it say approved or does it say 'recommended'? There can be a big difference 'recommended', by who, the company selling it? Think I'm exaggerating?
I don't think you are making it up.. I just think that some of it may not be 'important'.
IE. your argument of wording, reccomended vs approved and your suposition of reccomended by who? the seller. Ok.. throw that at approved.. approved by who? the seller. Both would be at issue.
Now enter in a tractor not made for 60-70 ys, orphaned for the most part except by limited legacy parts support, or completely orphaned . It's not like there will be an oliver or massey harris dealer to set around and test and approve oils.
Look at the oils in use in 1939... I don't think you can find a modern oil today that won't exceede what a 9n left the factory with.

even if it is the cheapest, weakest add package available. While we are talking oil.. remember.. if a bottle lists a spec, you hit liability if you lie. IE. if a bottle carries a API rating, or other similar specified ratings, if they don't at least meet, then you have lawsuit material. I believe it was supertech a few years back that had a mis labeling feature, and you better believe they got called on the carpet for it.
When it comes to UTF, and cheap utf here are 2 things I see .
1, cheap utf.. IE, the 19-25$ for 5-6 g pails. You see a marginal oil that has a BAD viscosity index.. IN other words, it will be like jelly when cold, and won't meet modern rating standards or change intervals. However... in the case of an old tractor... the old tractor wasn't designed around modern ratings and change standards!
While I would not put 19$ utf in my brand new John Deere or New holland 40000$ 90hp tractor working in FLORIDA, I wouldn't think twice about putting it in a 1939 ford 9N. The viscosity won't matter, as the original hyd oil was also a GEAR oil, so it's already expecting a thick oil , and by design they used a scotch yoke pump, not a vane pump.
To evidence this. you see some UTF pails that don't actually list a spec, they will just say suitable for non modern tractors. Very likely a save face for having an out of date or out of spec oil. For instance, see an cheap UTF listing a JD 303 spec? That's a QUITE OLD spec back to when they used SPERM WHALE OIL!!!!! Again.. wouldn't put it in my 2004 New holland.. but wouldn't mind it in my 1970's era yanmar! ( that called for that spec! )