Hi Mimisk and welcome to the forum!
Congratulations on your new addition, kudos to you for adopting this kitty, offering her a loving home
Glad to hear she is eating and drinking normally now.
As for the sneezing.. hard to say what might be causing this. As the discharge is clear, and she seems fine otherwise.. I'd suggest just keep her under observation as you're doing. If it continues.. you might take her back to the vet for allergy testing.
Some Persians. especially those that are extreme- faced (very flat) have a type of noisy breathing.. snorting, snoring sounds they make. It's not health related, but due to their tiny noses, as your vet mentioned.
In severe cases, where the breathing appears restricted.. I've heard of surgery being done to expand the nasal passages. But in most instances, this is not necessary at all.
If she actually sneezing rather than snorting though.. that is not connected to her breed.
I have a 7 year old Persian who is a pretty intense snorer, but she doesnt makes sounds at other times.
Good luck with your new sweetie, she sounds like a lovely girl!
We all love pics here.. would be great to see pics of your kitties.