The server side scripts for mech and turret seem to have survived in the client, however the mech respawn part doesn't seem to be part of them. Could also be a simple timing thing - there are still parts of the spawner networks in the luz files we don't understand, possibly there is a longer respawn timer set somewhere. The script for Survival seems to have survived too (surprisingly), so implementing enemy waves is technically possible, though without Movement AI it's lower on the priority list.
The more problematic parts are the newer (free to play update) parts of AG, and Crux Prime, Nexus Tower and Ninjago, since it seems from some point on LEGO figured out that including the server scripts in the client wasn't that much of a good idea, and thus the scripts for these worlds are missing.