This paper articulates an approach to incorporating instructor feedback in design-based research. Throughout the process of designing and implementing curriculum to support middle school students' debugging practices in a summer computer science workshop, our research and practice team utilized instructor-generated conjecture maps as boundary objects, providing insight into the instructors' reflections on their classroom teaching. We develop an analytic tool for categorizing instructors' reflections on their conjecture maps, attending specifically to how instructors push back on design choices, whether by envisioning new mediating processes, introducing new connections, discussing new design features, articulating confusion/uncertainty, and/or presenting hopes and predictions. The tool is then applied to seven instructors' daily reflections over the course of four weeks of instruction, focused on three conjecture maps. Overall, the paper documents a range of tensions that instructors encounter when aiming to provide sustained debugging support to students and introduces a tool for understanding the detailed ways that instructors critique design conjectures.