Is it safe to add raw eggs to homemade coffee creamer?
It depends on how hot the coffee-egg mixture is (and remember, adding it will cool the coffee), and how long it stays at that temperature.   

Given that coffee does not benefit in flavor from being left around, you want a fast process, which means the mixture should be at 160 F (71 C) for several seconds at least... it can cool after that.

Since coffee optimally brews at about 195-205 F, this should be in the realm of possibility.