her builders Mayer Werft in Papenburg, Germany are still in business and they certainly will be able to provide one with every drawing of the vessel built and (cross!) launched there as MV HOMERIC, provided they were willing to.
You should give it a try and contact them anyway. They might help a model boater out of his plight.
See their website
for contact details.
However, if you are out of luck there you could try the Assoziazione Navimodellisti Bolognesi
who also used to distribute a plans set of COSTA EUROPA, as she was named later while sailing for Costa Crociere many years, consisting of a general arrangement (1:200) and a body plan.
I know because I had ordered it a couple of years ago and the drawings seem to originate from the original builders Mayerwerft (i.e. showing no model building constructional detail).
Unfortunately, as I just have visited ANB's website, I haven't been able to proceed to the page of the COSTA EUROPA item order No.
The index page of ANB reads a note in Italian that their site is currently under construction and that this may last a couple of weeks.
So maybe you ring them up to inquire if the plans set is still available from them?
Then you could, of course, also inquire with Costa Crociere if they still have some remnant plans copies of COSTA EUROPA available that they would spare.
If that all doesn't succeed I could scan my plan sheets at a local copy shop and mail them to you for a nominal charge only covering my scanning expenses.