HN user
You can search & replace all occurences of a word with the substitute command.
Type : and write `%s/user/account/g`.
Although you won't get a real-time preview and will only see the changes after they've happened, unless you use a bunch of extensions(I use nvim).
Is it really silly though? The author of trace.moe has to label and store each anime episode somewhere, and use CPU power provided for free to search through these indexes. Adding regular TV series and movies to this dataset could really dirty what gets returned when the service is just about letting someone find out what anime some screenshot is from.
The FAQ says they've indexed most of post-2000 anime and very little of 80s and 90s anime. It mentions you can even use a similar drawing of the scene to get a match, due to the method they're using!