API - Back in stock open / clicked rate

Hello people,

I’m trying to export all my data from Klaviyo inside AirTable in order to centralize every tool i use ! (which is time consuming for me)

But i’m blocked regarding Back In Stock flows.

Here is what i’m trying to achieve :

• My shop is working with pre-order and i’m using Back-In-Stock (BIS)
• In the API, i retrieved people that are subscribed to BIS for a specific product.
• But now, i want to know for a specific product what are my open rate / click rate (mails are sent by the flow BIS)

As it’s a flow, i tried to retrieve the opened email metric timeline based on message_id of the flow but i can’t know for which specific product it’s related to.

Here is what i get from the timeline endpoint (metrics : Opened Email)

{
            "event_properties": {
                "Email Domain": "gmail.com",
                "Client Name": "Gmail image proxy",
                "$event_id": "my_event_id",
                "$_cohort$message_send_cohort": "cohort_message",
                "$attribution": {},
                "Client Type": "Other",
                "Client OS": "Linux",
                "$message_interaction": "message_id",
                "$message": "message_id",
                "Campaign Name": "Back in Stock: Email #2",
                "$flow": "flow_id",
                "Client OS Family": "Linux",
                "Subject": "Your product {% catalog event.VariantId integration='shopify' %}{{ catalog_item.title }} {% endcatalog %} {% catalog event.VariantId integration=\"shopify\" %}{{ catalog_item.variant.title }} {% endcatalog %} is available !"
            },
            "uuid": "uuid",
            "event_name": "Opened Email",
            "timestamp": 1616577321,
            "object": "event",
            "datetime": "2021-03-24 09:15:21+00:00",
            "person": {
                ......
            },
            "statistic_id": "statistic_id",
            "id": "event_id"
        },

My workaround was :

• Trying to read the subject of the email. But as it’s a flow, there is only variable like :
  Your product {% catalog event.VariantId integration='shopify' %}{{ catalog_item.title }} {% endcatalog %} {% catalog event.VariantId integration=\"shopify\" %}{{ catalog_item.variant.title }} {% endcatalog %} is available !

• Filtering by date (with the endpoint export) : but as i’m launching several Product in a month, the open / click will not be accurate. For Received Email it will work, but not for open/click

Do you know how can i find a solution ?

Or is there a way to custom event_properties inside flow’s messages ?

Thanks in advance,

Thomas.