Although I agree with you i am still leaning towards building new capital city.
Yes we definitely need new alutsista and stuff, and Kalimantan would be easier to invade, currently most of our military power is concentrated in Java and also population in Java is huge (huge potential of militia to support the military).
Short term solution is pergeseran kekuatan, long term would be bigger defense budget = more shopping = more alutsista.
they need to build several class A Air Force base in Kalimantan to start with
Java has Iswahjudi and Abdur Rahman Saleh, along with Halim Perdana Kusumah to protect the capital city of Jakarta and important city like Surabaya and Semarang. Not to mention the existence of Soerjadarma, Atang Sendjaja and Adi Soetjipto base as back up base and Kodiklat.
the only class A air force base in Kalimantan is Supadio in Pontianak, at the end side of west Kalimantan. They need more than Supadio and the supposed back up unit from Hasanudin Makassar as Hasanudin forces is intended to backing up Eastern Indonesia region. If Anang Busra, Dhomber and Sjamsoeddin Noer can be elevated into class A Air Force base along with organic fighter units that's will increasing Indonesian security as a whole. Kalimantan in my opinion is a strategic choke points as an unsikable carrier, along with Natuna and Maluku islands.
By the way to put new capital into Kalimantan in my opinion it will be a strategic move to securing Indonesian heart and vein aka Java. Even if enemies can destroying the new capital (god forbid) by launching long range strike missiles or air force bomber/fighter raids, we can always back off to Java and starting over again.