Dear Yong,

> I have a further question. bya~njana is a neuter noun, if
> lokahita applies to bya~njana, it should have been
> bya~njana.m lokahita.m, am I correct?

No. If bya~njana and lokahita are both taken to be nouns as
in my suggested translation, there would be no call for them
to agree in gender.

Best wishes,

Dhammanando