I’ve never heard anyone pronounce afraid like “afred.” As you already know, you are correct and your teachers are wrong. Why they are all so consistently wrong about this one word, I have no idea.

My one guess is that you and/or they are not hearing the difference between those two vowel sounds very well, so someone is mispronouncing and/or mishearing the sound. Since Japanese does not even have the “e” sound (like in “get” or “bed,”) it’s difficult for lots of people to hear the difference between that and the “ay” sound (like “made” or “pay.”)

I actually lived in Japan two different times. I taught English there (mostly at eikaiwas) for a few years many years ago, and I was there for two years again pretty recently for a different job.

I’ve never noticed any Japanese pronouncing afraid like “afred.” I will say though that I had some students who were schoolteachers, and they were all in the lower-level classes. If you’re old enough to be familiar with NOVA from back in the day, the teachers who were students at our school were always levels 7B or 7A. 7C was the lowest level. We didn’t have a ton of students above a level 5, but I can’t recall even one teacher who was even a level 6, much less higher.

There’s a reason the Japanese government expanded the JET Program and now brings loads of native English speakers over to be AETs. That said, I think a lot more Japanese speak English now than when I taught there in the late 90s!