You can buy in Fee Simple, which is how I'd want to buy anyway.

What they have is not uncommon. Fee Simple for most property (which is what you think of when buying property) and leaseholds for the rest. For example, in Palm Springs, if you buy on any of the Native American land, it is not Fee Simple, it's a Leasehold. Cheaper but you don't actually own the land, just the improvements. And you renegotiate the contract every X years, so buying a leasehold that is coming up for renegotiation can be risky. A foreigner can't buy a leasehold, but those aren't that common in Hawaii.