My flasklings aren't happy

[Undergrounder]

Hi everyone, i recently bought a few flasks of a few different things and i've been trying to grow them in my bathroom - The biggest, brightest, and humidist room in the house. It's got high ceilings and a skylight and it really does look like its suited for low-light orchids.

I water whenever the top inch of the medium seems dry, which is usually 2 - 3 times a week. On hot dry days i tend to spray the plants with an ultrafine mister. I have a single tray that has a plastic lid like a seedling propagator that i used for the first few weeks after deflasking to keep the humidity up for all plants. Since then, some plants are in, some are out, some are in compots, others in individual seedling pots. I've been experimenting with a small range of media, but all of them grow in predominantly Perlite, some have 1 part Vermiculite and others have 1 part bark.

I recently added a little half-strength Hi-K fertiliser to their drink every other watering.

I've got some Phalaenopsis schilleriana, Den kingianum and Cymbidiums. All of these are suffering the same problems, although the Cyms to a lesser degree and the Phals moreso:

Lots of them have started to get soft lower leaves, turning brown then mushy then becoming a mould risk. I pick them off at this stage.

Others plants have developed brown tips and/or the leaves have started to look weak and curled or pleated as if they haven't had enough humidity.

In a few random plants that i pulled up, i noticed black sections, that may be root rot.

Can anyone help diagnose what is going on? I know my setup isn't perfect, for one fresh, flowing air isn't the best. I try to keep humidity high for the Phals, but at the same time i seem to be having rot problems.

Pics attached. Note the black root-tips and dead leaves on the Cymbdidium (PIC 2), the sickly looking Phal leaves and the black/white marks on the Phal roots (PIC 1). The last photo is the largest Phal flaskling in the collection for a comparison.

Thanks