There is a way to take the values of rise and fall by task defined by an api or connected to the database.
If you are asking about ways to get backup reports, maybe some of these will help. If not, could you clarify?
The first link has the fairly simple outputs Duplicati can make. The other two third-party tools build on them.
A web API does exist but is mainly for browser GUI code to have the raw input/output interface that it needs.
Duplicati Client is a third-party command-line client that uses the same API, for those who need such a tool.
The databases certainly contain information, but the wrong sort of access could interfere with Duplicati use.
I will review and comment.