Potting Medium for Cymbidium & Miltoniopsis

[scy]

I received a cymbidium and miltoniopsis potted in a terrestrial mix.

My growing conditions:
- Temperatures: 40-50 degrees F at night, 55-65 daytime on cloudy days, 80 daytime on sunny days.
- Low humidity

I keep a wooden skewer in the medium to help me determine when I need to water next. Lately, I have pulled out the skewer and noticed some white spots on it. I'm guessing it's mold but not the fuzzy type.

The miltoniopsis was last watered Jan. 23 and the cymbidium Jan. 8th. I was concerned about the cymbidium and unpotted it 2 days ago to check root condition. The roots are still white and pump. The cymbidium leaves are light, grassy green and firm.

Do I need to repot using a different medium or should I leave it as is, since there is no rot? If I do need to repot, can I repot in chc only?