Water is a volatile, and you have quite some there. I don't know what exact products you used so it is very difficult to predict if it is going to shrink or crack. Well, it would be difficult even knowing, being a mixture, and will also depend on the volume etc etc.Good questions. The water is part of the chemical reaction in the plaster that makes it set, so there are no volatiles or off-gasses. The reaction is exothermic though so maybe pour in parts for a large enclosure in case it heats up enough to deform/melt the plastic.
I don't expect cracks to be an issue. The wood glue is added for the purpose of making the dried plaster less crumbly and its encased in the plastic walls with the gyroid fill in between to lend its support too. If you were to drop a dried speaker, then it might crack. I can CT again after "x" amount of time to confirm this theory though.
It is just a suggestion to have into account.