Your first Hoya looks like Krimson Princess Hoya (Hoya carnosa 'Rubra')
Your second Hoya plant looks like Krimson Queen Hoya (Hoya carnosa 'Tricolor')
The leaf problem appears to be a fungal issue to me and that, as well as the mold is probably due to the heavy soil that the hoyas were planted in at the nursery. Many nurseries plant in a fairly heavy, water retentive soil to keep the plants from drying out while in transit to garden centers around the country and many garden centers have employees who don't know one plant from another and just water at random. I've seen one garden center locally (a big box store whose name I won't mention) with plants sitting in water and an employee still watering them! I've seen another garden center with plants so dry that it appears as if they haven't been watered in a month or more!
Hoyas require a very well draining soil that allows good air circulation around the root system; wet humid conditions and heavy soil, with little air circulation will cause mold and fungal issues as well as root rot.
You can remove the damaged leaves and also scrape off the mold from the top of the soil. Test the soil by sticking your finger about an inch into the potting medium and do not water again until that first inch or so feels dry. Be sure to empty the bottom tray of any excess water to keep it from sitting around the roots which will cause rot and the eventual demise of the plant.
Ground Cinnamon is a great natural anti fungal solution and after you scrape off as much mold as possible, you can sprinkle cinnamon powder atop the soil. I live in Florida where it's quite humid most of the year and I grow my few hoyas in a mixture of potting soil and orchid bark mix ... a chunky combination which allows for good air circulation around the plants roots but during our rainy season, my orchids and sometimes hoya plants will sometimes have fungal issues so I keep a container of ground cinnamon in my gardening supplies!
I'm sure others will be along with more advice and suggestions real soon but I think your plants will be fine as long as the soil doesn't stay too wet.