Lindsey where/how did you find theme-lib.ui-script.profile-card =)? I could be wrong, but doesn't sound like an OOB component to me, which would mean you can't use @override on that, which means you will not have the <@delegate /> directive available which will give you that error (probably)...
As far as I have seen it, the profile-hovercard (you mean that "tooltip" that pops up when hovering over a user-name, right?) is usually implemented by professional services as an endpoint (find these under /t5/bizapps/page/tab/community%3Astudio%3Aendpoints in your Studio), look for one called "profilehovercard" or something alike...in there will be some freemarker/HTML markup where you should be able to find your target HTML, e.g. your
<i class="lia-fa lia-fa-angle-right">
that you want to replace.
In other words: The profile-hovercard is NOT an out-of-the box component, it's (afaik) a customization commonly done by PS. The hover card is also not implemented as a custom component (at least in my experience) which is why you can't override it as regular OOB components with @override.
let me know if that helped!
If you point me to your production community, I can tell you the exact name of the endpoint.
Okay I wasn't sure, I came onto this project after it had been worked on for a while so I wasn't sure where that component came from. Thank you!
