how were copies of vinyl made in "third-party" countries

Generally, as you have found ..original copies from the smaller orignal country can sound quite amazing. Mostly due to the possibility of the shortness and simplicity of the tape-to-LP path.

Regarding EMI/Harvest analog originals...those from Great Britain (smaller home town advantage) can many times sound the best. Eg, you generally wanna consider buying early Black Sabbath as a British pressing, if you can find a mint one. And the same for a few hundred other artists from GB. Good luck with that....

the trick here, is that the Canadian copy generally sells right along side the US copy, on ebay.com and ebay.ca... and all things being equal, like price/costs (which they are not always), the Canadian copy can be better, more often than not.

but, a thousand other un-researched situations exist, so..it is what it is...

The desired abbreviations may be on the lacquer and sometimes are. but deciphering their meaning is not easy as the language shorthand is their own internal company language and each is different.

...and the entire mastering to lacquer might take place at each pressing plant, or just some pressing plants. Again, depends.

A lot depended on how many units they thought would sell. If caught short they may run the stampers longer or make new masters.

is there a way to tell if an LP is likely to sound better from looking at it? 

The answer is no but I always looked for coarse grooves. That shows they were changing the pitch for more dynamic range but there are good sounding records that show even spacing also. 

My wife being a professor of German history means we spend a lot of time in Berlin.  Love buying DDR records like on the Amiga and Eterna labels.  Not the best SQ but fun to see what they allowed.

To add a bit to the cacophony, in the 60s, 70s, and 80s, where you sometimes had the same performance available on Decca, London, and/or Angel labels, one always knew to seek out the British pressing over the US pressing. Same went for EMI vs Capitol.

I know a lot of audiophiles in Hungary, they swear by US LPs and CDs as if God created them. The grass is always greaner....