There are several incongruities in your posts. To be clear, the enclosure is CMU coated with adhered veneer? If so, there should be no direct path of expansion from the oven to the enclosure, and thus nothing the oven does will cause the enclosure to crack.
Secondly, you do not mention insulation under the oven, is there perl-crete there?
Curing is very important, and as manufactured ovens get more popular it is even more important. Ideally, an oven will sit in a warehouse for a month or three before being shipped to a customer to allow it fully (chemically) cure and attain a moisture content commiserate with the ambient humidity. A green oven of cast refractory should not really be fired for at least a month after production, and then should be dried with tiny fires before firing.
The important part of a curing fire is to start the fire small in order to heat the entire mass equally and slowly, then step it up gradually to avoid thermal shock (those chips and pieces like you have). That is to say, when the oven is green, not only is the amount of moisture a problem but the material itself will not have achieved the strength needed to withstand the rapid expansion from heating.
All that said, you will be OK, so long as it is insulated under the oven, and you ease off, if not refrain, from any more fires until the oven has fully cured. The spalls and cracks are mainly aesthetic issues at any rate.
