Some have said,
Why would one want to make a TT hydrofoil? It will always be inferior (less efficient) compared directional hydrofoils
A bi-directional hydrofoil will never be as efficient as a directional, but there is a significant negative aspect to conventional hydrofoils, jibing. Some people find surfboards fun, while the majority of kite surfers are annoyed by having to jibe them and don't have the time, skill, or patience to learn how to jibe, so they use a twin tip.
I think the same is true with hydrofoils. Yes, there is an efficiency trade-off, but if the trade-off can be minimized thru continual development, then there will be a market for people that want to ride over the chop instead of thru it and have good lightwind ability, while not having to learn how to jibe or get wet every tack.
I think Hawaiis progression will help make this a product that will eventually come to market, especially if the cost is much less than current hydrofoils.
Here is my understanding of the history of bi-directional hydrofoil kite board (please correct me if I miss something).
chemosavi surfacing bi-directional hydrofoil (~2005)
Barney Townsend surfacing bi-directional hydrofoil (~2008)
don pitcher low cost bi-directional hydrofoil attempt (2008)
Wavy 2013 Hydrofoil
Hawaiis low cost bi-directional hydrofoil (2013)
I find this exciting. I hope this progression continues. I Hope more people jump into progressing this idea and low cost hydrofoils in general.