Powdery substance, brown spots on Maxillaria

[Bud]

you are right, its probably mold....peroxide will kill it....
your Maxillaria have nice plump bulbs and the roots are healthy....one mechanical issue on one bulb looks like a small animal took a bite....the Phal leaf was also eaten and chewed upon but the roots are healthy....all you need to do is continue with your care ....you have the right instincts about your plants....good luck