No. Riveria had already learnt at least one congenital magic but when she gained her falna she still had three magic slots.

Does it show up on status?

Why would it when it has nothing to do with the falna?

I see, thanks

What is congenital magic?

Magic learnt by the Elves based on their own innate magic affinity, without falna. It is explained in the Magic page.

Ok thx @RighteousWEEB