This is my two satang's worth on the subject of "live translations" provided by Thais who happen to speak English.

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I hate to rain on anyone's parade

, but what you don't want is a Thai native who grew up here and just happens to speak English

. To a person they are completely unable to break out of that "Thai Mindset" (which means they follow the often times oxymoronic thai cultural rules which dictate conversations here).
These types of translators often "water down" what you're saying in English when they translate it into Thai so that they better follow "Thai rules of conduct". This can and does lead to a loss of comprehension and a loss of emphasis on what you want to say versus what they're really saying in Thai to the person for you.
If you can be lucky enough to find a Thai who grew up in the US and is back here now, you'd get FAR better results that going with an English speaking Thai who grew up here.
I've sat in on a few people who secured the services of "live translations" from English to Thai and what was related in Thai had only a very loose resemblance to what was said in English. You definitely need someone who will say what you "mean" instead of what they think you want to say or what they think is appropriate to say given Thai cultural restrictions.
It's not as easy as you might think, although there are enough businesses out there who tout their services as if it's the greatest thing since sliced bread. Sadly they yield very little "bang-4-the-baht" in terms of quality.
I do know one Thai kid (I say kid because he's 22) who grew up in Texas, speaks and understands English like a native American English speaker (as in he knows idioms, cynicism, sarcasm, rhetorical questions, etc) and would probably be a "good fit" for your needs.
Given he's a Thai national, he is well aware of "thai cultural protocol", and seeing as he's Thai, he'd be compelled to act within them, because even Thais who grew up abroad are still locked into that mindset

. However, his understanding of English is far and away superior to Thais who grew up here.
If you're interested, P/M me with at least a rough idea of the specifics as far as the content of the expected translation, I'll see if he's up for it and put you two in touch. Seeing as he’s going to college, and knows what he bi-lingual ability is worth, he probably ain’t gonna be bottom of the barrel price range. But as my grandfather used to say "Good work is not cheap and cheap work is not good", so only you can decide what you're willing to pay

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FWIW: While I can speak Thai easily well enough to be understood by almost any Thai I interact with about any subject which I'm interested in; if I needed a “no misunderstanding” type of translation between me and another Thai, That kid would definitely be my first go-to choice.
"Whoever said `Money can`t buy you love or joy` obviously was not making enough money." <- quote by Gene $immon$ of the rock group KISS