Symptoms
People Picker Results Inconsistent with SP
Diagnoses
When using people picker, the results does not provide a "top match" like how it is in SP. See attached screen shots (from SP, search.png and search1.png) versus K2 (search_k2.png)
Resolution
You can also build out a custom K2 control using those open SharePoint APIs. I created a feature request on our end for our developers to look at for a potential control / enhancement for a future release.
Let me know if there's more I can do on this end.
https://help.k2.com/onlinehelp/k2smartforms/devref/4.7/default.htm#k2_smartforms_custom_controls.html