I don't get why the desktop app still doesn't allow you to select specific files. Am I the only one who wants to do that? It's a pretty standard feature in every other torrent client. Now that libtorrent supports WebTorrent protocol, I don't know what the value proposition of the WebTorrent desktop app will be.
If it's the latter, it's not going to work because the torrent needs to be seeded via WebTorrent(i.e. WebRTC). The desktop version of WebTorrent can download both regular torrents and web torrents because it's not limited to WebRTC for peer connections(whereas a browser is).
Put some gloves on and help out. Maybe you could get your features on the roadmap.
A lot of people in your situation hire a developer to add custom features. If your skill level isn't as high as the work required it could take forever (making you homeless). In your case (low skill/custom requirements) it is best to invest with a professional developer who can make your dreams a reality.