It’s totally okay to wish someone Moroccan a happy birthday, there is nothing wrong with that.
Now for celebrating it, it depends on families’ habits. There are families who make really fancy parties and stuff. There are those who would make a cake and have fun at home without inviting anyone, and the majority just let the occasion pass by without any celebration. It’s not really part of our culture. I wouldn’t even be offended if no one wished me a happy birthday ;).
Here is what we say:
3îd mîlâd sa3îd ??? ??? ??? = happy birthday. [same as in MSA]
bTôlt l3omr in shâ2 Allah ??? ?? ??? ??? = with my wishes for you to have a long life.