"Turn left at that place."
Translation:E huli hema ma kēlā wahi.
From what little I know, both i and ma mean in/on/at so your phrase should be okay. Ma tends to be a little more specific than i, so perhaps ma is preferred in phrases where X marks the exact spot. :-)
‘Ae. But I do not believe there is a defined set of rules on this. I think native speakers strictly use "ma" as stationary and "i" as moving, but today's learners are using them interchangeably.
For DL moderators, the difference between "i kela wahi" and "ma kela wahi" is the word "at?" In order to be exact, what would be a proper English word in order to use "i" in this case? I suppose one could say "Turn left by that place" although awkward. Is that when you would use "i kela wahi?"