CUSAT and other government and private colleges that come under Tier 3 should not be your top priority. There are many Tier 1 and 2 colleges that are less opted. Such institutions include- Anna University, Jadavpur University, PSG Coimbatore, and VIT. These are relatively much easier to get into and offer a 100% placement, in contrast with CUSAT and other Kerala government colleges/ universities. Other options may include Delhi University and Panjab University.
NITs and IIST are top institutions. They should be your top priority. If you wish to go abroad, your college tag holds even greater significance. You will get into masters’ or grab a job abroad way more easily with a good college tag. If you can qualify for CUSAT or other Kerala government colleges, you can easily get into any of the institutions mentioned above. Moreover, the grading system/ credit system in most of the government universities in Kerala is bad. It poses obstacles in your admissions in top universities abroad. This is especially true for European Universities because there is a lack of proper credit transfer channels.
Thus, I would say that CUSAT and other Kerala government colleges are not very good option and should not be at the top of your priority list.