If you are planning to return the plant, then I would not do anything more to it. If you plan to keep it then cut the spike where it comes out from the plant. Use very clean sharp pruners.
The catleya media is loose and looks like is has good air spaces, but some of the bark looks whitish, which is a sign of buildup of calcium. The dark black parts of the roots is not healthy and the roots at the base also look spongy and dead. However, I do see the tip of the root that is hanging over the pot does still have a green tip. Be careful not to damage that root. The other root looks like it was injured at some time in the past. Eventually, it will need to be repotted but it is better to wait until the new healthy root is stronger. The young growth still looks o.k. and that is where most of the new roots will come from. Again, use either rain water or filtered de-chlorinated water if you can. I think you have been watering too much. Make sure the orchid media is nearly dry before watering. The light looks o.k., the leaves that I can see are a medium green. You can dust the roots with cinnamon. It won't hurt. A monthly fungicide would be better. If you are going to fertilize, use the orchid water soluble fertilizer or Peter's 20-20-20. Dilute it to 1/4 strength and you can spray the roots when you water. It can also be sprayed on the leaves early in the morning when the stomata are open so they will get some foliar feeding. The leaves need to be able to dry, so make sure air circulation is good. Indoors, a fan helps. If you can carefully cut off any of the obviously dead and soft roots you can reach.
Normally, I would take the plant out of the pot and cut off everything that is dead and stick the plant in a basket. You need to be careful not to damage the new growth or the good roots.
As the media ages it breaks down, and bacteria and fungal organisms thrive on decaying media. That is why most orchids should be repotted around every two years in bark. Orchids in nature actually depend on certain species of fungi for their seeds to germinate so they actually invite fungi and bacteria. However, the bad as well as the good fungi and bacteria show up to the party. Commercial nurseries fungicide orchids once a month routinely. Dithane is the fungicide I usually use if I can get it. Subdue is better but requires a license and is very expensive so I don't have access to it.
I water a lot, and I get a lot of root rot if my orchids are in bark and pots, so I get around that by using baskets and pots that breathe like net pots and clay. I use media that does not break down easily. Styrofoam, rocks, cinders, or no media at all.
I put most of the cats in baskets and tie them to the pots with large bark, sometimes a wrap of long fiber shagnum moss to keep the initial roots from drying out to fast. or I will tie the orchid to the bottom of a smaller pot and put the smaller pot in a larger terra cotta pot and let the roots attach themselves to the empty pot. This allows me to 1. not have to repot for a very long time. Bad part, they can get very big and hard to remove from the baskets. 2. I can get away with watering daily or biweekly. I water when the roots are white and as long as I see a green tinge, I can wait a little while longer. I hang most of my orchids on trees or on the fence since it maximizes air circulation and allows the roots to dry quickly. This best imitates how they grow in nature. Catleyas are epiphytes that grow on tree limbs with dappled light. In the rain forest it rains every day, but the roots are attached to the outside of the branches for support but do not dig into the branches at all. The roots are exposed and are like sponges when it comes to capturing light and water. Being high up on the trees they also get a fair amount of the breezes that come by so the roots do not stay wet. Orchids in pots are in a hostile and unnatural environment. In nature, orchids can be very unruly growers twisting and reaching through the trees with roots hanging out everywhere. Only people want orchid roots to be confined to a pot.
Most orchids are happier on a raft. It takes a little patience in the beginning to get them started. Orchids are tied to rafts. Usually a branch, cork, cedar board, or even a cedar shingle for a small plant. My friend uses old panty hose to tie the orchid to the board with just a small wad of sphagnum moss to provide moisture until the roots have a chance to grab hold of the board. Once the orchid roots have engaged the raft, even if the tie rots off it is fine. Rafts are usually hung up and the orchids can be misted or watered almost daily as long as the air circulation and humidity is good.
A tea bag filled with orchid food or even chicken manure helps to fertilize orchids every time they are watered. Water soluble orchid food should be given during the growing season (when the tips of the orchid root are green). Weekly,weakly works well. For outdoor orchids we usually water twice a week depending on rain. Once a week, half strength water soluble fertilizer is given for 3 weeks and the 4th week is only water to flush the plant out. Do not fertilize when the plants go dormant or over fertilize or the plants will grow at the expense of blooms. Indoors, it depends on humidity, air circulation, media type and how long it dries out.
This is not to say that I don't kill orchids. I do. I kill a lot of them. Often, I wait too long to repot an orchid and it there isn't much in the way of roots or eyes to save. I try anyway, sometimes it works, sometimes not. I am trying to get the orchids I obtain out of their pots sooner and into media and pots that better suits the way I culture. Even if I do everything I can to keep the plant healthy, I have snails and roaches that love to eat orchid roots and leaves as well as birds that will eat the orchid buds and petals. I just found a bird stuck inside of my orchid bench because it could not find its way out of the shade cloth. I have to experiment with locations. I know some types don't mind being in the sun, most like to be hanging in the trees, and some of them I keep on the lanai, since they need more shade and they don't like wet leaves. I have an abundance of orchids that really like the growing conditions and I have some that have the tenacity to hang on no matter what challenges they face. Those are the keepers. Others, well, they come and go. I sometimes just have to find the sweet spot for them, so I keep trying.
https://firstrays.com/free-information/ ... -root-rot/
https://www.skyrail.com.au/news/orchids ... ainforest/
https://www.aos.org/AOS/media/Content-Im ... rchids.pdf
Happy gardening in Hawaii. Gardens are where people grow.