This is my first post

We are new hermit crab owners, actually they are our first pets. Three PPs as near as I can tell that we adopted from my daughter's friend (They had too many pets). I did not know what we were getting into but have quickly done some research. As best I can tell, they have been living on pellet food, with tiny fresh water dish, on less than an inch of sand in an open lid container for three years. I think it is a 10 gallon tank? I don't think they have molted at all? Maybe one surface molt, but I think they through the exoskeleton away.
I've been reading the crab care sheets obsessively...
In the week and a half that we have had them, we have changed a lot.
-6 inches of sand mixed with coconut fiber disk thingies to sandcastle consistency
-UTH on side of tank backed with cardboard for insulation. Saran wrap over top of tank with opening for air. Temp 78 F, Humidity 80% (hygrometer calibrated yesterday)
-New kinds of dried food from trusted etsy sellers listed in food section of this site, plus some supplements from my mom's organic garden, plus cuttlebone in tank
-salt and freshwater pools - bigger than what they had, I'm not sure they are quite big enough yet but I'm working on it. I have been using distilled water from Walmart in gallon jugs and Brita water because I was told these were safe. I know now I need to fix this. I have Betta Bowl essentials and instant Ocean arriving tomorrow.
-new turbo shells for everybody. So far the only one who swapped permanently was my biggest guy, Sam. I don't know how to measure them but he is probably 2.5 inches as best I can tell measuring distance between his outside legs.
I'm having trouble getting them a hide they like. Their old one was really smelly so I got rid of it. I tried one made of grass for small rodents and they loved it but I was worried that it was going to take moisture out of the air and rot quickly. So yesterday was kind of a big day. I put in a reptile safe faux wood cone, added a lot more (reptile safe) moss for humidity, and added the Saran Wrap at the top. The first time we put them in the deeper sand, they ran around kind of panicky but soon settled down and hid in their old hide. Yesterday they panicked as well. So far they seem to hate the new hide and will not go inside voluntarily. Batman, still in his painted shell from the store, has made a cave in the sand under the moss I brought in yesterday and I'm of course nervous but excited. He's the first one to try any digging at all and he didn't look gray or have a molt sac so I hope he is going to be okay. I just lifted the moss a tiny bit to peak and put it right back down!
So I'm wondering if I have changed too much too soon. I should probably chill on the changes for a few weeks, huh?
Should I take the new hide out? Can I give them the grass one back?
Thanks for any help you might have. I know it can be annoying to constantly be teaching newbies and I appreciate the effort!