Hi there,
From what I can find, the configuration has to be static and cannot include dynamic data. This is further backed up by the documentation ( https://docs.mendix.com/howto7/extensibility/charts-any-usage/ )
"The configuration can be set statically, via the Source attribute or with the Sample data."
This might be a limitation with the current implementation of charts in Mendix?
Other solutions have been found to export charts that don't use static configurations (https://forum.mendix.com/link/space/studio-pro/questions/115213). This could help with your need to have today's date in the file name.
Hope this helps,
Liam