Don't rely 100% on the Apex conductivity probe for your salinity. Always double check it with a calibrated refractometer and clean all the probes every couple weeks. Just a quick soft bristle brushing while still underwater in their holder is all that's needed. You'll be surprised at the changes to the readings.
I think you're a little early in the game to be using an AWC system. Letting the tank mature more before using that will help. The system will use up Alk is it goes through the cycling as you can see from your current Alk level, it's the bacteria doing it's thing. An AWC is not going to replenish enough at this stage of the tank maturing. There's several cycles aquariums go through the first year to 18 months, it's not just the initial nitrogen cycle. The things you do can extend or shorten those cycles. So don't over complicate the system. The first 6 to 9 months follow the KISS method. Keep It Simple St...
You don't have corals that are going to get upset by a couple of large water changes and doing those will help reset the tanks parameters, beyond just the Alk.
I would also ease into the CUC, but you definitely need some snails. Get a dozen or so Banded Trochus snails and the same amount of Cerith snails. A Turbo or two wont hurt either, but a lot of them will only end up starving them all in a short time. As you go, you can always add more CUC and it's better than them starving and dying. Which not only sucks for them but the decay will dump nutrients. You've got a big enough tank for two conchs I just don't know if it's been up and running long enough to keep them a steady supply of food. Watch their activity for anything usual and maybe target feed them occasionally.
I've not a huge fan of hermits. But there are many that swear by them. I've found that that are all too willing to kill snails for their shells. If you go that route start small there too 15 to 20 blue legs. Another thing that will help is adding some pods if you haven't already.
The BRS series of vid's on the WWC tanks have a lot of good info. If you haven't, watch them a time or two. I still think that adding a bunch of corals right after the ugly phase is a very good idea, which is what they elude to. It's just not something I'd recommend someone new to the hobby to attempt. There's still a lot for them to learn.