So it's not like she's easy to get to. Or even predictable. Between both of the engineers that I have, I've talked to Kaye maybe a dozen times. And almost every single time, Kaye has nothing to sell. Limited supply recipe, of course.
As I write this post, I am hoping that Kaye restocks before she goes to the "unresponsive" state. For anyone not familiar, Kaye has a timer for restocking like all limited supply vendors. But she also has another timer -- after a certain period of time she'll simply stop talking to you. My guess is that Kaye's unique status with the unresponsive timer (unique as far as I know, that is) and limited supply recipes is to prevent someone from farming. But I have to say... dumb.
There's a really easy way to make it so that engineers don't flood the market with these schematics. Bind on pickup schematics. Poof! The only ones who can get to Kaye are engineers. The only ones who would need the schematics are engineers. And if you can use the wormhole generator, your engineering skill is far above what you'd need to learn any of the recipes Kaye sells.
No more limited supply recipes. No need for unresponsive NPC timers. No worries that you'll get that rare chance of going Underground and not actually being able to buy the schematics. And lots and lots of other vendors sell BoP recipes, so this wouldn't even be a difficult coding issue.
TL;DR: Please make the schematics Kaye sells BoP, with unlimited quantity, so on the very rare chance that my engineer can go underground to talk to her, they can actually learn the schematics.