I use spreadsheets to hold information that I later use VBA to export to Word for the purposes of publication with this line:
wordApp.Selection.TypeText MY_STRING
There's way more to it than this, but this is the heart of it.
Is it possible to use VBA to send to Scribus?
I have not visited this forum for many moons. I am upgrading my Ubuntu OS. So it is by chance that I can reply.
If you have external variables to inject into Scribus sla format then I do recommend that you explore ScribusGenerator
https://github.com/berteh/ScribusGenerator (https://github.com/berteh/ScribusGenerator).
And in general explore the Scripter (python) functions in Scribus top tool bar.
Later thoughts ..
If you have extensive works written in VBA then perhaps pyxll might bridge between VBA and Scribus/Python scripting. Caveat: I do not use VBA. Google Sheets, for example. has a Python API.
https://www.pyxll.com/docs/userguide/vba.html