I would suggest to read the Transvideo monitor manual!
especially pay attention to page 35-37
found it here:https://tips.zgc.com/tips/PDFs/Instructions/Transvideo_CineHD_Operator-Manual_evol_1.1.pdf
If you use the Transvideo internal color scheme - these treshholds can be adjusted and will be different than on ALEXA. I would turn the false color off on the monitor itself and turn the false color on in the ALEXA monitor output.
Then the colors will match.