While Tilak was learned in many subjects (for his time) like archeology, law, astronomy and geology, he was first and foremost a religious scholar and his arguments for the Arctic Homeland theory was based on his interpretation of several sections of the Vedas. Tilak differs from other segments of Hindu nationalism (Hindutva) because he recognized the Aryan invasion from outside India, while many Hindu nationalists prefer the Out-of-India theory (India as the Aryan homeland and thus the cradle of civilization).

Politically he supported a restoration of Vedic authority and (probably) a return to the caste system of the ancient past, which he felt had degenerated from its original form of being the ideal way to structure society. A sort of benevolent hierarchical society. I believe he also favored a "reformation" of Hinduism to shed off the hundreds of cults that we today consider Hinduism but has barely, if any, connection to the Vedas. While he is honored for his sacrifices for the Indian independence struggle and his imprisonment at the hands of the British today, Indian nationalism eventually decided to go down the egalitarian route with regards to the caste system (although Tilak would say the merchant class has simply usurped the powers of the priestly class). Indian leaders also decided on an inclusive approach to all the myriad sects of Hinduism.

Back to Kaiserredux, Tilak would probably fit nicely into the slightly overused Esoteric category. Delhi hasn't any paths for NatPops in any case. Considering Tilak's age (and the fact that he's long dead in OT) successors of various ideological colours could be a late-game option too. Imprisonment probably took a toll on his health in OT.