charghwI':

Dun [Qap yuQDaj ‘e’ tulbogh nuv].

SuStel:

This is grammatical and is the correct formation for what he tried to say.

There's something I can't understand in this sentence. The subject of
the {-bogh} phrase is the {nuv}. But what is the object of the {-bogh}
phrase ? Is it only the {'e'} or is it the {Qap yuQDaj} ? Or are they
both the subject ?

The object of tulbogh is 'e'. The entire relative clause consists of a sentence as object construction, Qap yuQDaj 'e' tul nuv, with -bogh added to the main verb, tul.

The entire subject of the sentence is Qap yuQDaj 'e' tulbogh nuv person who hopes that his planet succeeds.

This aside, could we extend

Note the difference between grammatically possible and wise.

 the correct {Dun [Qap yuQDaj ‘e’ tulbogh
nuv]} to net, neH sao's and to quotations too ? Suppose we write:

Dun [Qap yuQDaj net tulbogh]
someone who hopes that his planet wins is great

No, because the relative clause has no head noun.

Dun [Qap yuQDaj neHbogh nuv]
the person who wants his planet to win is great

Yes, so far as we know. But as with all of these, it's confusing and probably not a good idea.

Dun [Qapjaj yuQwIj jatlhbogh nuv]
the person who says may my planet win is great

Yes, with the same notes.

Is there something wrong with the above sentences ?

Yes. They are too confusing to be understood without stopping and parsing them. They're like the following perfectly grammatical English sentences:

The horse raced past the barn fell.
(The horse fell. The horse was raced past the barn by someone, and then the horse fell.)

The rat the cat the dog chased killed ate the malt.
(The rate ate the malt. The cat killed the rat. The dog chased the cat.)

Buffalo buffalo Buffalo buffalo buffalo buffalo Buffalo buffalo.
(Yes, this is a grammatically correct sentence. It means, basically, Bison from Buffalo, New York, who are intimidated by other bison in their community, also happen to intimidate other bison in their community. Buffalo is the name of a city in New York, the name of an animal species, and a verb meaning intimidate.)

-- 
SuStel
http://trimboli.name