I looked back through some old posts but didn't find an answer to my question, which is:

What RH is recommended for the roasting space/room?

I'm pretty sure there are no recommendations. We could be missing the forest staring at the leaves, with something like this.

If you're roasting on traditional gas, you're creating water vapor anyway. So the true environment the beans are encountering are going to be different than what a meter will tell you about your roasting space anyway.