The text book I'm reading teaches as below.
Correct: I have as many books as you.
Wrong: I have books as many as you.
OK, that's understood. I think "many" here is not an adjective, but a determiner.
I tried to come up with a sentence of such structure and these below are what I conjured up.
Yet, both sounds wrong to me.
(1) I smelled as sweet roses as lilacs.
(2) I smelled roses as sweet as lilacs.
I would just say "Roses smelled as sweet as lilacs." in a daily conversation.
I cannot think of any good examples of this structure.
I don't understand what you're trying to say in either 1 or 2. Your version that you call 'conversational' is perfectly well formed; I don't think it means very much though
The version that your book marks wrong could be fixed by the addition of a comma.