Sync data from Excel to SharePoint custom column list

I am currently working on a SharePoint site where I have two Custom site columns, BU and Period.
BU has a list and sub-lists with business units and departments, Period has a list of years, 4 quarters and the months of the year.

When I store an Excel file in a library, I can select a BU and Period for the file and the selected options also show in Excel f.i. (File - Info - Show all properties - Period) shows 05 (May).

So far so good, but In Sharepoint, this shows as 2022;Q2;05 (May).
Why are the year and Quarter not visible in the Excel CustomProperty?
How can I load the current full data to Excel?

The next question coming from this is:
How can I alter/fill the BU and Period data to be loaded back to SharePoint?
I have tried and change the month, it is visible in SharePoint, but when I reload the file in Excel, the old data is diplayed again.