GF just bought the January issued of "English World" magazine. Somehow, every instance of the letter pair "fi" is missing. For example, "first" is rendered as "rst", "firms" is "rms" and "office" is printed "ofce".

I imagine this must be driving lots of English language students crazy....

I suspect someone was attempting to change the "fi" pair into it's ligature for typesetting purposes but forgot to include the ligature when doing the search and replace.

I wonder which proofreader will get the blame?

Nobody will get the blame. This is Thailand, where only farang and Burmese and drug dealers get blamed.

Thai publishers and Thai ajarns are too proud to have their work corrected by a non-Thai. Usually.

Also, while Thais can do a great job of very impressive presentations for special ceremonies, on routine non-essential unimportant things like schoolbooks or education, they're prone to throwing a bunch of crap together and never looking back. It's almost as if they think their audience is a bunch of dolts.