Takeo/Prey Veng dialect. Used near the border with Vietnam. Cannot be written in Khmer script.

Is this written with the IPA, or is it how native speakers write it?

IPA, there is no standardized spelling, online posts can range from "ortn" "rorn" "ort" (the last one simply based on អត់ /ʔɑt/ in standard Khmer)

One serious drawback of using IPA is that native speakers without linguistic background might think they aren't supposed to join the project.

I personally think we should use IPA only if native speakers never write the language.

I dream of the future when one native speaker of the dialect adds the variant "ortn", which he uses himself, and then another native speaker of the same dialect adds the variant "rorn", which she uses herself.

Perhaps tommy_san is right, about using the different Romanized spellings. However the issue is that unlike Roman and Japanese script, Khmer script is highly respected and thus "forbidden" to be used to write slang or vernacular speech. For this, Roman script is used, but never in teaching materials, only in normal speech (which is what we WOULD like here on Tatoeba).

Maybe in the future the stigma of adding slang/vernacular in teaching materials will be lifted and we will see more of this speech.

There is much standard Khmer to be added, and my wife and I will work hard on adding them, but if any tourist uses this standard Khmer to speak to the locals, they will be laughed at a bit.

So be it, if Tatoeba is not ready for Khmer slang/vernacular, then we will withhold for the time being.