I understand that in Australia, there exist in each state a trust of JW's that holds ownership of all the Kingdom Halls. The titles or deeds are all sent to the Bethel's Legal Department in Sydney and kept on their file.
If the local congregation wants to sell the KH and then upgrade their hall, they need the permision from Bethel, then The RBC, and obviously the trust need to sign off on the deal too.
Now though with greater financial powers going to the RBC, if they were to sell the old hall at a profit, they might be "encouraged" [forced] to donate that profit to another project instead of being able to sit back with some cash in the bank for a rainy day.
So really, the locals build and pay for the KH. They willingly/begrudgingly hand the Hall over to the trust, who sned the deed home to where it belongs!!
Note though that due to their Goods and Services Taxation system the loans are "interst free" and why shouldn't they be, it is all donated money and lets face it, the WTS get a free KH.
It is a wonder they dont borrow money against the equity in all that property and do some very heavy duty investing....say cigarettes, alcohol, armaments... ;-)