how do you want it to be any other way?
do you want to overwrite existing enemies just so the exported ones can have proper ID's?
if you want change ID numbers for those first ones, you have go update every command prompts anyway.
The point I was making is that importing the sandbox level into the project
results in a broken gamewith incorrect references to enemies.
The solution to this is non-trivial and there are various ways to solve this (e.g. have a different ID system which are not using simple numbers that can overlap between sandbox/project).
One way would be similar to what happens when you convent assembly language to machine code and resolve JUMP type instructions.
What could be done is to scan through all the sandbox command lines that reference an ID and
"tag" and/or "mark" these entries, then when the sandbox code is merge into the project and
objects (such as custom enemies) are assigned their new IDs the "tags" are updated to reference the new IDs