Citroens (of old) used LHM hydraulic which always came with a warning not use in other non Citroen applications. Delving into the web to find out why . .
Seals for conventional brake fluid are a natural rubber blend which is not resistant to hydrocarbon fluids, like LHM. However, seals for LHM will be a nitrile rubber blend which resists oil based (hydrocarbon) fluids and will also resist conventional brake fluids.
Thus it would appear that save for the thread and sealing flare detail Citroen spheres could be considered.
Perhaps someone with a spare Honda sphere from a converted system could measure the thread?