The energy stored would be the area of the pressure volume diagram cycle. Assuming a constant or average volume, the energy would be pressure times volume.

https://en.wikipedia.org/wiki/Pressure–volume_diagram
A 2.5cm radius pipe that is 7 meters long is 13.7 liters. There are tires with about that volume. Multiplying 13.7 liters volume by 100 psi yields 9,476 joules of energy. (Type "(2.5cm)^2 * π * 7m * 100psi" into google to get that answer.) That's about 2.6 watt hours. It isn't energy that is the problem. It is power, energy per time. If you release 2.6 watt hours in a second we get (2.6 watt hours x 3600 seconds/hour) = 9,360 watts. Do it in half a second and we have 18,720 watts. More than sufficient to cause injury.

Long thin circuit batten(s) like used in popup shades could be used instead of inflatable beams on the leading and trailing edges. Wider struts could provide floatation with less drag penalty. This idea is now in the public domain and un-patentable. The circuit battens can be offset from the edge for safety, and there can be multiple circuit battens.

https://www.ikea.com/us/en/catalog/products/30228978/
Bruno's high pressure kite design also uses bridle system more similar to foil kites than LEI kite to give shape under tension. It isn't a stiff leading and trailing edge that is needed, with a foil kite type bridal system. Something to hold open the kite to get tension on the bridles quickly which give shape to the kite is what is needed.