> You could simply put the feminine form in the dictionary.  That way
> you'd only have a few irregular adjectives, which didn't remove the
> final consonant in the masculine (before consonants).

But there's also the problem of the "liaison": |un grand homme| is
pronounced /9~ gRA~t Om/ whereas |un homme grand| is pronounced /9~n Om
gRA~/. Therefore you'd need to put three forms in the dictionary.
But even in the standard orthography there are some irregular feminines:
favori/favorite, dissous/ dissoute etc.

> Still, French doesn't need a massive reform.  Its pronunciation is
> largely predictable from its spelling.

But the spelling is not predictable at all from the pronunciation. That's
the starting point of most of the more serious reform proposals. I'd
appreciate a reform based on the IPA, but the one I proposed is a little

>  But I would like the word 'fils'
> to be spelt 'fisse'.  Am I right in thinking that 'fils' is one of the
> few nouns that comes from the direct (rather than the oblique) case in
> French?

Perhaps. That's filus without the u.