As per the title, are refunded items and cancelled sales also counted in the total transaction count?

I don't think so. It's referring to the total proceeds over a calendar year, so refunds should be deducted.eBay will share your data with the tax authorities when, in a calendar year, you have reached EUR 2,000 in sales proceeds or completed 30 transactions. from: https://www.ebay.it/help/selling/selling/direttiva-dac7-legge-sulla-trasparenza-fiscale-delle-piattaforme-obblighi-di-comunicazione-materia-di-vendite?id=5394&st=3&pos=2&query=Direttiva%20DAC7%20e%20legge%20s...

DAC7, do refunded items and cancelled sales count? | Selling on eBay

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DAC7, do refunded items and cancelled sales count? | Selling on eBay | eBay Italy