Does Duplicati Not Work Well with Too Many Files/Files with Strange Names?

Are you using the recent –usn-policy option? That got some fixes recently but they’re on total path length.

Issue 3311 PathTooLongException when using USNJournal #3456

https://forum.duplicati.com/t/release-2-0-4-3-canary-2018-11-13/5279

PathTooLongException when using USNJournal #3311

Regarding file limits, there aren’t many reports (maybe your invitation will get some) but I did find this one:

Capabilities and limitations? near 1 million files

If you can select shorter pieces out of your error messages, perhaps posting them will get some input too.