in the whole watering scenario you really have to think about gravity and how water works. you also need to think of where the roots are.
these are not new plants, they are fairly well established and then put into a bigger pot (5 gal) so the roots are not on the bottom, and knowing how gravity works, the water is lower than the roots (read @Aqua Man watering post and note the perched water table) and that makes it pretty hard to over water at this point.
dont worry about phing your tap water, the soil you use will buffer it to 6.3-6.8 no matter what you do (mostly).
maybe when you transplanted you put her lower and those leaves are getting "watered" and then sitting on the moist soil.
right now they look like they want some water. i would also raise the light, any time they are not feeling so great raising the light wont hurt them and might stress them a bit less. or dial back the intensity. i think you might have a bit of stress from the light change. as she responds then gradually put it back.
watering when young and in the first pot is very important, understanding why and what you are doing it for, helps. always remember the first root the lady grows goes straight down. the branching and winding around happens as she fills the space with roots. but the first one, first thing, goes down till it cant, when you water gravity makes much of the water hang out at the bottom, the dirt sort of wicks up some and it stays moist a little over the table, but the root goes down, the water goes down so it works out. that is a good reason to put it in a size appropriate pot, the root only has a short ways to go to get to the bottom and start winding around and making a good root ball.
so if you water to keep the top inch, or finger or some other measure damp, down at the bottom, where the good stuff is happening, the little roots are drowning, they cant breathe! so, for me, picking up the pot to check the weight is the best way to know when to water. in soil, water till you see the first drops come out, water slow enough to notice!
when you up-pot, you move the root ball from the bottom to the middle. so watering needs to change but just a little and just a little while. this first water in its new pot is important. you need to water slow and soak it (again, for soil, just till a tiny bit runs out - but slowly so it all gets hit). then let it dry but watch her, she will tell you when to water. after a watering or two it is back to normal.
keep in mind that different plants at different stages have different watering needs. it is difficult to put them on a schedule, when she is growing great she is drinking lots.
all in all, your change of light likely has something to do with this, but she will recover and she looks like she will be a pretty plant after this hic-up