I suspect you should have repotted them long before you did, but you probably know that now. I can't imagine Sansevieria growing to a 36" height in mostly perlite -- it's just too light to hold anything. Pumice, maybe, but not perlite. If they were mine, I would pot them up separately in several pots, different mixes, hope for the best and see what happens. For myself, my Sans grow in a variety of mixes, but essentially 1/4 to 1/3 C/S soil, 1/4 to 1/3 chicken grit (I use Manna Pro Poultry because it's readily available) and usually the rest is either pumice or a combo of pumice and perlite if I am trying to lighten the pot. They are not fussy about the soil. I repurpose soil for my Sans and they don't complain.

You probably WILL have to stake them until they get established. From the looks of your photos, that could take up to a year, IMO.

Your plants look pretty good. They need a root-and-rhizome system. My best recommendation is gradual introduction to GOOD sunlight and warmth if you can get it, NO wet roots or cold roots, a mix that drains well and a pot with drainage. These plants are hard to kill. Chances are, yours will rebound.

Very nice looking plants! When you put them back in a pot, using a few rocks around the soil surface can keep the leaves upright.

When I had mine, I used tomato cages. Mine got over 4 feet tall and now they sell them painted green and would look very nice in the pot.

I think they’re gonna lean no matter the soil. I use compost w/perlite and after a while they lean. I also use tomato cages. When pot looks too crowded I divide and share, usually keeping the shortest for myself.