lol, I wouldn't call myself a super expert, I'm just an information junkie
If the inserts are microfibre (the fluffy white material) then it could be what's called compression wicking - basically microfibre will soak up wee quickly like a sponge, but, like a sponge, if it gets squished a bit then the moisture will come back out again. That's why I asked if she was a tummy sleeper, since it's coming out the front. Side sleeping can put pressure on the front of the nappy too, as can putting dome up bodysuits over the top of the nappies.
I would consider teaming the microfibre with something that will soak up more slowly and not let it go, like bamboo or hemp.
I would also check the fit, esp since they are OSFA. Are they adjusted with snaps at the front?
Are they brandname nappies that we'd recognise? Can possibly help you more with the fit side of things if we know what we're talking about