Hmm, no, it doesn’t. No idea why you believe that. It works perfectly fine with https url.
I don’t really understand the rest of your comment as indexing and metadata look ups are done by the server and not the client. Plus Swiftfin uses VLC under the hood so it shouldn’t have issue with playback.
Are you using the fairly recent stable version or are you experience on an older development version? Swiftfin has been officially available for only a month.
If the indexing and metadata is done by the server, then the server just is worse than Plex at figuring out what things are.
I can't tell you why it crashes when I try to play back videos that work just fine via the web interface, but it does. They're normal 1080p h264 .mkv files.