Do you mean THX? A standardisation of image and sound quality that was needed for many theaters who weren’t showcasing movies in a good quality in the 70s and 80s? If so, that started around the time of Return Of The Jedi, although it wasn’t until around the mid 90s where the smaller theaters, independents, or those located outside the major cities installed or subscribed it? Probably due to the installation costs involved, and annual charges like technicians showing up once or twice a year to check and approve the theaters were still adhering to the specifications?

There’s a little more on this, here:

https://en.wikipedia.org/wiki/THX
https://www.lucasfilm.com/news/lucasfilm-originals-thx/
https://originaltrilogy.com/topic/Info-Wanted-Did-the-THX-logo-accompany-Return-of-the-Jedi-in-theaters/id/47301
https://www.reddit.com/r/movies/comments/15a6hes/whatever_happened_to_thx_certs/ (see VisibleEvidence’s post)

The reddit post above has some of old tricks some theaters used do to save money, and not show films in their best light.

But there’s probably more on THX etc in the Star Wars Preservation forum on here? I hadn’t heard of there being specific requirements for TPM, but could have been (other than the “block booking” aspect for TPM by Lucasfilm mentioned in your linked article). I got nothing else.

If you find anything please post it up in here, it’d be interesting to read up on.