Phal Black Roots... PLEASE Help! (+ A Side Note...)

[NeonKraken]

Hi! Hope everyone is enjoying the holiday season About a month ago, I cut all the dead roots and repotted my sick Phal. A week or two ago, I was pleasantly surprised to find that the two leaves had grown, and a new root had sprouted from the lower part of the orchid. Today, I was surprised with three more roots, but quickly disappointed to see that the very tips had turned a brownish-black. Some most of the root(s) are still green, but I am a little worried, as this orchid has been sick before. I have it by a sunny window and it is planted in sphagnum moss. I'd appreciate it if someone could tell me what is going on here.

*Side Note* I have noticed that my orchids planted in sphagnum moss in potts have been taking a lot longer to get dry lately. Is this just because of the cold weather and should I water them less over the winter, or am I doing something wrong... Please help. Thank you so much.