Tagging this for
chef jimmyj
to read....I know he is fascinated by the dry curing process...and might have some perspective on the safety side...

23mm salami is very forgiving and easy to dry. Very hard to get case hardening because the diameter is so small. The larger you go, the more case hardening becomes a problem.A friend puts 100 pounds of 23 mm sausages in a 4x4x4 box with good success. Garage temps are perfect in Jan thru Mid March in Missouri - 30 to 60. Rainy days sometimes and sunny days sometimes. Just put in a Humidity gauge in the box and close or crack it during the day... night temp bring up the humidity and leave it open and watch the weather. Sunny warm dry day in Feb.. close it or crack it to keep humidity from going to low too fast.. Cooler rainy days.. open it up. It all averages out.
Looks like a tad of dry rim, but not bad. Looking back at your chamber set up, I see what looks to be two computer fans on the floor of the chamber. Are those running continuously? If so, what speed? Salami needs less and less airflow as it dries. If the airflow is more than 4 inches per second than I would try to slow it down or turn them off. Too much airflow can cause dry rim/case hardening even if temp. and humidity are optimum.