Hello and welcome to frog forum!!
Poor frogs! It's a good thing you have her now
don't worry too much about coco fiber, it's usually easily passed through the frog's digestive system.
The tank size is not too big, she won't get too stressed as long as she has plenty of places where she can hide and feel secure
I don't think that the hydroball drainage layer should be necessary for this species however. The coco fiber should be damp but no so much so that water is accumulating at the bottom. This species does not have extreme humidity requirements so damp coco fiber but not soaking wet is more than enough humidity. Save yourself the extra work
i used to use coco fiber and naturalistic beddings in all my enclosures but now I only use paper towels as substrate that i spray once or twice a day for my frogs. I find it's a lot easier to maintain and a lot less work. Doesn't look as nice though. Up to you.
You've really done well with improving the conditions in her enclosure! Nice work!