For any who want to know-
For a 100% or close enough germination straight to rockwool you need to find a guide on the best way to place your seed in the hole. Its on the net somewhere but i cant find it atm. It describes the seed placed in sideways so end to end but i cant remember which way the seam ran.
Some growers took a long time to work this simple trick out and highly recomend you find it.
Yes rockwool germination is tricky at first but after a few hundred attempts it gets easier than soil.
A real pro rockwool tek is to wet the cube and lay the seed pointed end right next to almost over the whole. Forget your paper towels, the cube will soak and self root for you.
Other stuff that will help is an understanding of how a tap root anchors, it uses the root hairs that grow off it. Initially the tap root needs downwards pressure to push into the substrate. This helps you get it secured.
I love my rockwool, shame im mainly a soil grower, once you get rockwool down you will have so much fun but first its a freaking nightmare.