I too am using duplicati with Jottacloud (not sure how many of us are there). Recently my home windows server ran into issues after a windows update (CLASSIC!) so I started the process of restoring the image backup file that was backed up to Jottacloud using duplicati (I could have also restored the backup files using the local drives attached to my server but this was a good test case). I installed duplicati on my laptop, entered all the info to restore the files straight from jottacloud and ran into issues (this was a large restore…i think like 300gb or something like that). After the restore “finished”, none of the data was actually restored and got an error for basically every single file (can add the specific details later). I didn’t bother trying to further troubleshoot the issues since it took so long for the restore to even fail. Not really duplicati’s fault for taking so long since I think the download\upload speed for Jottacloud is quite gimped when using duplicati (I find I can get 20mbps down when using the jottacloud app) however a little frustrating to have to wait so long for a message indicating nothing was restored. I then proceeded to use the jottacloud app to download all the encrypted files first and perform the restore locally which worked without any issues at all.
Anyway it was all in vain since apparently the version of software I was using to perform my image backups doesn’t really work for my use case (windows server 2016 essentials running as a DC) so I ultimately ended up having to rebuild the OS drive from scratch 
This however gave me a new opportunity to test the “adoption” process of duplicati on the rebuilt machine (don’t really know how else to put it since that’s what crashplan called it and that’s what I’m familiar with). That process went very smoothly, which consisted of recreating the backup jobs I had previously made (learned my lesson and now have the configurations exported and backed up), running each backup job for the first time, it failing, running a database repair and then running the backup again.
Anyway, as a new user to duplicati, and Jottacloud for that matter (just started using them like 3 months ago), I really do like it.