you are aware of the nature of RH vs LH thread? French is typically RH, but some
adopt swiss also 35mm but LH thread

Kludging a fixed cup remover, a collection of industrial hardware,
was shown on Sheldon's tips,
there are other specialized tools that hold a fixed cup wrench on the fixed cup,
to get adequate leverage without slipping..
but, lacking adequate tools, jobbing it out to the bike shop for a few bucks is a bargain.