1) Brindavan was introduced to provide a fast connection between Madras, Bangalore and Mysore. A connecting MG service was operated between Bangalore and Mysore. With the BG and MG service being treated as one single railway connection to Mysore, it was named as 'Brindavan'. At one point, it was supposed to be extended to Mysore after the GC. The proposal never materialized, so the name now looks anomalous.
2) Mangala Lakshadweep - Well, trains are not named after reservation quotas. This train always had the name 'Mangala'. And since it passes through Mangalore even now, it's not really anomalous.
3)...
more... KSK via KCG - The 'Sampark' in SK refers to 'all classes' of people. While the Rajdhani concept was only limited to A/C class passengers, the SK concept was supposed to be an 'all class Rajdhani', and reach out to all classes of passengers - Hence the name 'Sampark'. And with Bangalore being the capital of Karnataka, the train was called 'Karnataka Sampark Kranti' - again, not anomalous.
Interestingly, the MYS-MV express now runs on the old timings of the Kaveri express between SBC-MYS.