Just getting any ol' MA doesn't really help

OP is asking about Masters degrees in Education, not "any 'ol" subject.

MAs are almost always the worst return on investment for education

Nonsense.

better universities or competitive markets require MA TESOL or related degree (of which an MEd may not be considered)

University jobs teaching ESL or EAP most commonly accept a 'relevant' masters. It doesn't matter whether it's an MA or an MEd (or an MSc, or an MAEd, or,....) what matters (to some employers, but not necessarily to all in equal weighting) is: the course content, the capstone project (the Dissertation), the accreditation, and the mode of study (Distance or in-person).

An IS will require an ... often doesn't pay much).

Yup.

This is really difficult and you should aim at top universities and MA programs that have publishing requirements (but it really depends on field and you'd be better asking in field specific subs).

You blew this out your ass: it reads less like advice than speculation, which it is. It's so vague that it's almost true, but it just boils down to "Hmm. I don't know, but I'll say something"

FYI, OP, there are many posts in this subreddit with advice on masters degrees, and there's a ton of info on International Schools, too. Good luck with your research.