Got these Calathea Musaica plants as babies, but as soon as a leaf matures... it dies.

I get new growth year round, but I cant figure out what's going on.

Used to have them sitting facing east window - moved because of the yellowing thought maybe they were bleaching. Have tried overwatering and monthly watering - only use bottled water). Pearlite mixed in. Have tried adding potassium. Was sitting next to humidifier, but removed that element. I did tranplant them into a larger pot after summer.

My Calathea Orbifolia is relatively new to my household. Have had it for maybe 1 month. Leaves are curling/browning. Only use bottled water. Pearlite and bark mixed into soil.

Fiddle Leaf is seeing growth at the top, but the leaves have random browning/dead spots that are very brittle. Maintaining great color. Sits still near a south facing window. Room does get a fair amount of light, but nothing direct to the plant.

Can anyone identify this tree? I need to know how to properly prune.

If anyone can offer suggestions or identify my problems, I'd greatly appreciate it!