Why not just restrict the limits yourself and tell people not to use PTB? If you're doing your own restriction then PTB would be unnecessary.
How are you adding spawns to world? From my experience with CSDM, Steam no longer allows you to create the CT/T spawn points. This may have change since I last tested in February, but creating them resulted in the player spawning at 0,0,0 and an instant crash.
CS is caching the spawns internally, along with all other entities it uses (to bypass FIND_ENTITY_BY_STRING or whatever), so no matter what you do it won't affect that internal cache.