So the CDMA system is generating spurious emissions after 890.0 MHz ?
The GSM system starts at 890.2 MHz (central frequency). Therefore you measure -76dBm at 890.2 MHz.
Trying to convince your government that the CDMA system is overlapping to much with your frequencies is going to be quite complicated. Your measures are not a proof good enough ?
You could check what is the theoretical maximum spurious emissions a CDMA system should generate outside its own band.
Does the problem occur only on GSM cells that are collocated with CDMA cells or not ?
If yes : you can try to install additional “sharp” filters in those GSM sites
If no : then you’re stuck… can’t you ask the CDMA to move their bands 200 kHz downwards ? That should give enough room for a good isolation.