Depends how hawt the servant is.
Like if it was a male servant that looked like Caesar, Fergalicous or Gilles de Rais Caster pursuing Ophelia, most would probably feel different about it. In this age and era I’m not sure if Napoleon’s antics are considered endearing or creepy by majority of the fanbase.
If the role reversal did occur I think the fanbase may like it even more because rarely is it portrayed in the reverse imo. But it also depends on our characters. I don’t think any current female servant would fit the bill to play Napoleon’s part. I don’t think any are that forward and persistent about romance. Off the top of my head possible candidates would be: Medb, Nero, Tamamo Caster and Kiyohime. Drake and Quetz may also be possible, but I don’t think they would be too persistent. Maybe Drake because she is a pirate and they like the thrill of capturing a tough treasure (treasure being the Crypter in this case).
Medb is more for flings so that takes the romance out of it for many. Kiyohime tends to be categorized as crazy in love so her portrayal may just be pitying of her at best while learning a very special lesson between love and obsession / mad love. Nero and Tama might be the best fit. They seem like the types who would already proclaim that the Crypter is their husband much to said Crypter’s confusion. Nero I think fits more of persevering to ask for a hand in marriage while I think Tama would be the type to try and get the Crypter to propose instead.
Most likely a new servant would have to be made to fit the part. So the story and her persona can be easier created around the plot rather than fitting in a current servant.