CUSAT has yet to receive an IIEST upgrade. The work is still on, and funds have been allocated to strengthen the infrastructure in the next few years. Being an ex-student of the college, I'm not sure when it'll be upgraded.
To answer your question, despite being an excellent college, the Ananda Krishnan committee has not recommended ICT Mumbai for conversion to an IIEST. Let me give you a list of potential causes:
The institute offers Bachelor’s degrees in B. Pharma, Food Engineering and Technology, Chemical Engineering, Pharmaceutical Chemistry and Technology, Polymer Engineering and Technology, Surface Coating Technology, Oils, Oleochemicals and Surfactants Technology, etc.