Bad roots on Neofinetia falcata

[Ember33]

Hello everyone! I am a new member and I would like to ask you for some help.
I recently received this blooming Neofinetia Falcata Beer that I ordered online, from a local flower shop. It was potted in fine bark chips and when I took it out of the pot to have a look, I've seen that it has a smaller division too. The leaves on the plants don't have wrinkles but at the base, some seem yellower.
The root systems on both the bigger plant and the smaller one, are not that great.
On the bigger one I would say is worse. Roots seem desiccated and the velamen is broken from place to place.
I removed only the paper dry parts and repotted the orchids in transparent plastic containers (with holes on sides and bottom).
I used a mix of large pieces of charcoal, pine bark and some shpagnum moss. And tried as best as I could, not to compact the moss.
Since I have zero experience with Neos, I wonder if I did good on how I repotted them. Would they do better only in sphagnum?
They sit on east facing windowsill where the temperature at the moment reach between 13-14 degrees Celsius ( 55-57 Fahrenheit).
A small humidifier is placed near them and the air humidity varies between 60-75% during the day.
Soon I will receive a heating mat that I plan on using with my other orchids (Tolumnias, Mini Phals, Ascofinetia).
Is it a good idea to places the Neos on the heating mat to stimulate their root growth? From what I gathered, they seem to like cooler temperatures. Also, how often should they be watered?
I understood that in the winter time they should not be watered very often. But in the state that they are now, I am scared I might induce dehydration and hinder the growth of new roots.