Possible to reload and edit Job

[Selur]

core.std.LoadPlugin(path="C:/Audio-video App/Hybrid/64bit/Vapoursynth/vapoursynth64/plugins/fillborders.dll")

Hybrid uses a portable Vapoursynth version, sadly Vapoursynth has no option to disable autoloading, so this really might cause issues, since Vapoursynth might autoload them.
a. In general, I would recommend to make sure not to put .dlls in that folder. ('vapoursynth64/plugins'; also don't put stuff in the coreplugins folder.)
b. If there are .dlls in that folder, they might get autoloaded and explicitly loading them will cause a crash.

clip = core.fb.FillBorders(clip, int left=3, int right=0, int top=0, int bottom=0, string mode="fillmargins", int interlaced=-1)

that will also not work, since it's not Vapoursynth/Python code.
it should be:

clip = core.fb.FillBorders(clip=clip, left=3, right=0, top=0, bottom=0, mode="fillmargins", interlaced=-1)

the types should not be in the call.

If you remove the 'def beforeDeCross(clip)'-section, you should also make sure to remove the invocation of that definition.

clip = beforeDeCross(clip)

otherwise, the script will fail since it does not know what 'beforeDeCross' is.

If you add random stuff to a custom section, you really should check the preview to see whether what you added really works.

Cu Selur

Ps.: recreating the job seems to be easier