See this post, and note how I handle accessing the template's custom properties:
update-row-in-template-repeater-using-button-outside-from-template-click
Also, in case your running into the pycomponent wrapper issue, see this post for a way around that:
why-cant-custom-properties-and-methods-be-accessed-from-a-component-that-is-obtained-using-swingutilities-getancestorofclass