I would say they have responded, although it appears that the latest build didn't resolve the issues for everyone. It is extremely difficult to fix something that doesn't always appear. They have to be able to replicate the problem before it can be resolved. As one Ultra owner who hasn't experienced these problems, I can't offer to assist via their beta testing program (although I am a participant). If you still have problems, offering to become a beta tester and provide your feedback to the fixes.
Beta testing for Roku is, from my experience, a near total waste of time. They do not listen to or respond to testers unless the testers report what Roku wants to hear. In my years in the program I never felt that Roku really valued their testers and they rarely even engaged the testers on the beta forum.
I do not think Roku really wants testers unless those testers are willing to only report problems that fit in with Roku's plans or are total show stoppers.
Roku was, and for now still is, the best streamer there is but their software is becoming more and more buggy and they are not taking steps to fix the bugs before moving forward. This poor quality control is causing Roku to be less of the front runner they once were and it is getting closer and closer to the time where some other streamer will overtake Roku in their first position.
I would not waste my time and energy beta testing for Roku but rather the time is better spent finding ways to make what now exists work better and in researching alternatives.