Trajectory planner is not an easy task, so i would stick with LinuxCNC for that (as do most companies using it) and do your HMI/GUI for it.
C/C++ is fine, React i have no clue (is that a version of Java script?), but whatever you end up using, make sure that if it crashes, it does not take the trajectory planner and real time stuff with it.
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For me reliability is paramount, so i stick with Axis GUI mostly, i distinctly recall some 10 years back messing with Linux deleting stuff while the machine was working, i broke something, screen went black, keyboard was not doing anything, but the machine went on to finish the part over two hours after blacking out!
Having industrial machines With LinuxCNC running 24/7 for nearly 15 years without ever having any issues is something big companies can not do, of course as most of those still use windoze!