Yes, I use unraid. While I could change to transmission, I wouldn't anytime soon. I like all of my client options with deluge.
Only work is changing your install file to include the extra packages and pip install the modules. The mod install sample I gave is the only difference between your docker and the one I made https://hub.docker.com/r/frozenpine1/arch-flexget-fp/ https://github.com/frozenpine1/arch-flexget-fp
If you add deluge and rar, I'll switch to just using your docker directly. Otherwise if you want to keep yours transmission only, I completely understand and ill periodically look for your updates and make my mods until I learn how to do a proper fork/pull.
"connect seamlessly to 2 different Deluge instances running on unraid." I'm doing this too.