Hey, I'm sorry your post never got replied to. You apparently have 66 subscribers so it seems unbelievable.
Maybe it would help if there were a "Sensory Issues" group, but for now I think the "Coping/Daily Challenges" group is probably the most logical choice out of the available groups, to talk about sensory problems, including chemical sensitivities.
As for your other suggestions, perhaps the "Adulthood and Autism" group would most appreciate topics like those. In fact, I would enjoy hearing what you have to say on those subjects in the chat room!