It's not that "Couatl is crashing the sim". Couatl, being an external .EXE simply cannot crash the sim, since it doesn't have any access to its memory. It's the sim that is crashing by itself, when it's creating lots objects (by itself), following a command sent by XPOI through the standard Simconnect interface.
Sure, we might have added some limit ourselves but the issue is, there isn't any documentation about how many objects the sim could display before crashing, and this is likely different between FSX, P3D (32 bit) and P3D4 (64 bit).
Also, when the data source is external, like in XPOI, it's difficult to estimate how many object will be created in a certain area. On some places, you could easily run with everything turned on, and won't display as many objects as another area with just a few classes so, it's probably best to start low, and enable classes one at the time, until you get to know how many classes you can use in that particular area. They are VASTLY different in density.