Okay, check this out: when the verb is the focus, we've had an insoluble issue with how to manage other sentence arguments. For example:
ni ma suo ka sumo
1SG IMPF eat DEF squash
"I'm eating the squash"
becomes, when the verb is in focus, what exactly?
suo sa ni pe ka sumo...ma?
eat FOC 1SG REL DEF squash IMPF
"I'm eating the squash" (stranded particle)
ma suo sa ni pe ka sumo?
IMPF eat FOC 1SG REL DEF squash
"I'm eating the squash" (just how much of the VP do I have to front?)
In this case pe becomes effectively a kind of accusative marker (literally "with respect to") for some pretty strange, not-very-Koa-like syntax. Yuck. But, so I just read, Basque (similarly sensitive to topic/focus) accomplishes this by focusing an unconjugated verb, then using a dummy verb in the usual spot with the usual inflection. Here's how that could look in Koa, with ete, possibly set to replace teke for "do":
suo sa ni ma ete
eat FOC 1SG IMPF do
"I'm eating," i.e. "it's eating that I'm doing"
Done: easy, elegant, totally normal-looking Koa. Note: this would logically require that ete suo be an acceptable usage. Maybe some kind of blanching or euphemistic force when not focusing?
Next up: how to handle topic. We've never figured this out.