I’ve been speaking English for over 40 years and without looking it up in a dictionary I couldn’t tell you what "-philic" or "-philiac" mean. To me, "HarryPotterPhilic" sounds strange and I’m not sure what to make of it...
A common suffix that means "fan of" or "someone who likes xxx" is "-phile". For example, "Bibliophile" means "someone who likes books". The opposoite of "-phile" is "-phobe". But "-phile" is usually used with latin roots - for example people don’t say "Bookphile".
I think just adding "Fan" would be much simpler and more easily understood. "HarryPotterFan mum" sounds good to me.