Are you seeing any changes in your babies at all? Are they doing something inside the cubes or can you not tell? 4 days seems long enough for them to show the first few leaves.....at least on one of them since you know they cracked and have a taproot.

I'm afraid I don't understand your germinator thing at all so I skipped over it......always done my mine in rapid rooters so I'm sorry but I'm just not sure about your cubes......and whether or not they are a problem at all. Wish I could be more help......sorry.