Just thought some of you may be interested in knowing since you gave up on clicking the translate button since it's done nothing for months.
The translate button for Thai is working again on both Facebook and Instagram!
As some people in comments have said it's not working for them yet, I'm assuming the feature is rolling out like many times features are added. So if it doesn't work for you yet, it should over the next few days.
TLDR : Answer Summary
The translation feature for Thai is reportedly working again on both Facebook and Instagram, after being nonfunctional for several months. Users have commented on their experiences, with some stating it is already operational while others are still waiting for the feature to be available on their devices. This rollout may take some time, as is common with new features. People are hopeful for improvements in translation quality compared to previous iterations.