Why is my sempervivum dying?

Your plant might be struggling because it's getting too much water. Try using a humidity meter to adjust the humidity and check the soil surface. If it's still wet, wait until it dries out, then water it. If your plant shows signs of distress, check the roots. There may be some rot, so you must cut the damaged part off and replant it with a fresh soil mix.

This plant's roots are experiencing some challenges. It's difficult to tell whether they're too wet or too dry. Let's reduce the watering frequency for now to give them a break.

Hmm, maybe you're not giving them the proper care? Sorry, I never planted this plant, so Idk what I should suggest to you.