Okay, I do believe its time we get a bit more serious on Ninfia, because I'm starting to look into things, and I can't see anything that would designate it to be a bug type or normal. First and foremost:
If the basis is off of a nymph, instead of Ninon as some are saying, it would also imply a new type as nymph could refer to the infant stage of an insect, or the mythological creatures of Greek Mythlogy that are happy dancing maidens that lure men.
Nymph (biology) - Wikipedia, the free encyclopedia
Nymph - Wikipedia, the free encyclopedia
Now then these 2 are likely however there is cause for doubt. Eevee evolves to adapt to its environment, and to whatever genetic mutation it encounters. Additionally the eeveelutions are likely to stay as are without evolutions, so I do not see the logic in it being a Pokemon based on the biological stasis before the metamorphic transformation before the adult stage. That would counter the whole concept behind this evolution family, and I doubt GF would go that far.
As for the nymph, I do believe Jubilant typing could be interesting, although lacking. All the typings of Pokemon have insofar moves that logically hurt you either physically or indirectly through the elements. Not to mention this would likely require happiness, and the eeveelutions Espeon and Umbreon already cover that evolution method.
Moving on to normal typing now. How exactly would the evolution work? Stones that could evolve would make no sense as it would technically already be available by Pokemon Logic, and again happiness cannot and will not be factored in. What else could pertain to a normal type eeveelution? Exactly...
Now lets take Ninon as the basis, which is silk.
Ninon - Wikipedia, the free encyclopedia
Ninon is a silk cloth, and what is silk? A fiber. Fiber would make for a good type as it is not only silk, but a lot of other organic materials. It could offer some pretty cool type combos, and unlike the happy type mentioned, physical attacks could spawn from this typing in a logical way. I do understand new types are a bit daunting but I do believe it could happen.