I'm starting the CF from SJPP on the same day!
I asked a similar question in another forum and got all sorts of responses but no real answers. After some thought, if this were to happen to me, that is if I were to develop mild symptoms with or without a test, I will probably not go through the hassle of reporting it to the health authorities (as some suggested). Instead, simply get a hotel room to self isolate until symptoms subside and take extra precautions going out to get daily supplies and food. I don't see the need to involve the local health authorities or even tell the hotel management, just take appropriate precautions.
if this were to occur near to my flight back home, I would definitely get a self test and if negative proceed with the official test. If positive, grit my teeth and extend my flight reservations until I test negative and then get the official test and rebook.
I am very much interested in what others have to say about this and whether there is some existing "official" procedures, so thank you for posting!