Sorry to hear you're still struggling with this.
Only thing I will add, is that in meantime maybe you could use this: https://github.com/userdocs/python-libt ... repository
Granted it's for Debian, but should be a static build of the libtorrent bindings, with libtorrent 1.2.7 and boost included, used with deluge2 from pypi(pip install deluge) so would only need python3 as dep, but don't know if it's somehow incompatible with non-debian installs, but sound like a viable workaround in-meantime, at-least to me.
Alternatively, then higher up in that link there's also a script for building this from scratch, though still Debian focused, but should be adaptable to your platform pretty easily(only thing i'm thinking is that it checks for missing deps with apt, so delete that part, and just install deps first before running it), but might as well firstly test out the pre-built versions, as per link provided.
Just a thought
Edit: For GTK-UI working with above, you need python-cairo and python-gobject installed, or whatever called on your distro, or alternatively, you could download and use the wheels I built little time ago of these, and install with 'pip install PathToWheel'(add '--user' after 'install' if having used '--user' also when installing 'deluge') and wheels available for both python 3.7 and 3.8: http://s000.tinyupload.com/index.php?fi ... 1773264450
Edit2: BTW, do you have any noticeable detrimental effects from your current libtorrent in deluge, other than UIs stating n/a for IP and lots UDP traffic when monitoring? I ask because I see often also n/a for IP in UIs(both with and without namespace tun0 lockdown), but works fine, so don't think that is a problem except cosmetically, and uTP and UDP trackers are preferred over TCP in libtorrent by default, plus DHT shows alot UDP traffic too, so was just thinking if there actually is an issue with your current setup? E.g can you successfully run the ipmagnet test to show announce IP, as that is specifically using TCP for tracker announcing: https://ipmagnet.tap3.eu