Language barrier is always a challenge when it comes to chemistry, but i do find that using key words with thai accent helps them understand better. This works in other countries and languages as well, even when i speak malay in indonesia, if i imitate their accent, itll be easier for them to understand me. Ive observed similar thing in vietnam, japan and korea as well.
One particular incident in vietnam made me realize this. I was ordering an ice tea, from the counter at the cinema, where they sell lipton ice tea in the bottle. After repeating few times in clear standard english, with him not understanding what im saying, i resorted to sign language and pointed to the bottled drink behind him. Immediately he says, ooooo "aih" tea. So afterward, i tried few times imitating their accents, and definitely improves the communication hehe.