It's interesting. Makes me think of
Esmeralda, kind of exotic/mystical, but I think Sarilda feels much more user-friendly. Looks like Sarilda is a variant of the
German Serilda. For both look and sound, I prefer Sarilda (I pronounce the "a" and "e" differently, so don't consider the spellings interchangeable). Rilda works well as a nickname. I did wonder if it was made up, but it's not so "out there" as to be ridiculous.