You may see some discrepancies between Klaviyo's web dashboard and the data you import into your spreadsheet using Airboxr. While Airboxr data should be directionally correct, they may not match to the last digit. 

Here is the core reason why:

Customized web dashboards may use different attribution models—Dashboards in the UI are customizable and therefore sometimes use different attribution processes. This is already on the Klaviyo Engineering Team's product plan and we will update our workflows when this is fixed. For those reports that do not use the message attribution windows, any event data (e.g., opens and clicks) are grouped based on the date those specific events happen. They will not be based on the day an attributed message was sent. This means that while reports/dashboards use Klaviyo’s attribution model to determine the dates by which to attribute data (based on the date the attributed message was sent), the individual event data of opens and clicks are grouped by the date that they individually occur. Learn more about Klaviyo's attribution models here

Thankfully, it seems the Klaviyo team is well-informed of the issues and are working actively to get the API and the dashboard to match each other.