Why do that h2->kerosene at all? Why not using the compressed h2 or something like https://en.wikipedia.org/wiki/Slush_hydrogen to drive a fuel cell(or an array of them) or a micro gas turbine, to power hyper efficient electromotors built with something like https://en.wikipedia.org/wiki/Rare-earth_barium_copper_oxide
superconductors in a holistic concept which is using the h2 to cool the superconductors? I think I've read something like that not too long ago, maybe even here on hn.
The idea for synthetic fuels is that they can act as a drop-in replacement for fossil fules, so you don't have to adapt the vehicles. I wouldn´t call using H2 a synthetic fuel, because it would require a different aircraft design (its probably more reasonable appraoch overall, although access to truly carbon free h2 is limited right now).
edit: Ah yes, see https://www.airbus.com/newsroom/stories/ascend-cryogenics-su...
addedit: Or less ambitious https://www.ainonline.com/aviation-news/air-transport/2020-0...