CAPITAL Office Business Software

I don't see an option on the transfer menu to import supplier transactions from a spreadsheet.

Is this possible?

You can do this by importing the transaction data into a card file that meets a specific format, and then open the card file and then from the main menu select Tools|Generate Supplier Invoices.

The topic "Card File Invoice Generation" discusses the specific technical set-up details (what lay-out your card file needs) in order to be able to do this.