I think it's pretty surprising for you to make that "Probably no Hiroshiaite" claim given that the linked-to Wikipedia article says it exists: "Following the atomic bombing of Hiroshima, it was discovered in 2016 that between 0.6% and 2.5% of sand on local beaches was fused glass spheres formed during the bombing." - https://en.wikipedia.org/wiki/Trinitite#Similar_materials

and when a quick search finds the relevant research paper at https://www.sciencedirect.com/science/article/abs/pii/S22133...

"A complex association of millimeter-sized, aerodynamically-shaped debris, including glass spherules, glass filaments, and composite-fused melt particles was recovered from beach sands on the shores of the Motoujina Peninsula in Hiroshima Bay, Japan. .... This study interprets the large volumes of fallout debris generated under extreme temperature conditions as products of the Hiroshima August 6th, 1945 atomic bomb aerial detonation. The chemical composition of the melt debris provides clues to their origin, particularly with regard to city building materials. This study is the first published record and description of fallout resulting from the destruction of an urban environment by atomic bombing."

and when the dynamics are described in https://www.sciencedirect.com/science/article/pii/S0012821X2...

"Our analyses support the hypothesis that the Hiroshima glasses are gas phase condensates formed in the nuclear fireball ... The Hiroshima bomb exploded 580 m above the city so that no crater was formed at the surface. The plasma (called fireball) formed at this altitude, had a maximal radius of 230 m (Imanaka,2011; Malik, 1985). ... The maximum temperature on the ground during the explosion was estimated to be 6287°C (thermal wave) (Radvanec, 2009) while the maximum pressure reached 35 tons per m² (3171 bar) at the arrival of the blast wave at the hypocenter, 1.3s after the explosion (Radvanec, 2009). Under such conditions, the city materials were injected as vapor or melted debris in the air 0.5 to 2 seconds after the explosion and vaporized by the high temperatures prevailing in the plasma (4000-2500 K) at that time (Adams et al., 1960, Supplementary S6)."

I think what your analysis didn't consider was the observation that "The fact that no crater was produced by the explosion (Glasstone & Dolan, 1977) reinforce the idea that the primary source of Hiroshima glasses is the city materials and not the soils or the basement rocks below the city."