After updated to 2020 version that added support to Asian languages (include Thai), it look like Indesign force user (in my case Thai) to set language in Advanced Character Formats to Thai. After set the language Indesign also require me to use World-Ready Composer to set all tone marks in place.
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Before the latest version, I always avoid to use World-Ready Composer because it combines a word to single object, not just locks tone mark and float vowel to character in the right position. By which it impossible to navigate with text tool to the position of text that I want to revise, even if I use right/left key to navigate. It mostly skips word by word, not only character by character. And when I delete a word or a character, some time it not only deletes backward but forward too. (I think because of when I delete character form a word Indesign instantly recognises new word and forces to delete that new word.) But After updated to 2020, I think, I anymore cannot avoid World-Ready Composer.
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After I designed to use World-Ready Composer, I found one more bug. Because in many situations when I craft the spacing in layout (especially in Thai), I always use thin-space to separate character like “ๆ” form word before and after to make the space between them look good. But After I set to World-Ready I found that when thin-space (include other spacial white space like en or em) is in the back of the line the spaces in question act like normal character, so the last character of the line when use left justify do not snap to right frame border. The space still there like It becames one of character. So you can see the gap between the last character and the right frame border. (you can find this instance in attachment in file “space issue.”)
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But the serious issue still there after the update. I, and all of my co-workers, found that everything about word wrapping in Thai language goes wrong after updated to 2020 version. This never happen in the former versions. I don't understand why this issue is happen. Even if I use Discretionary Line Break to help Indesign to wrap text properly. But It is not productive at all, because I had been forced to read text all over again and to insert Discretionary Line Break to every lines. (you can find this instance in attachment in file “wrap gone wrong.” In the high-light is the words that should be stick together.)
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PS. while I wrote this issue report, my co-worker tried to migrate back form 2020 to 2019 and she found that when copy revised text back to 2019 it not the same character encoding. I advised her to try to place that text to TextEdit. It appears that some character is changed to something that is not unicode at all. That never happen in previous versions too. ((you can find this instance in attachment in file “text form 2020” and “text form 2020.” the text form 2020 at frist did in 2019 before migrate to 2020.)