@Rishit Thanks for reaching out.
Unfortunately, as of now the custom tables are not supported. Some limitations are document here.
The salesforce connector logic is based on assumption that every table is derived from the default “Standard Object” type, which has an Id column.
The workaround would be creating your own custom connector and leveraging the REST endpoint from the salesforce end.
I will also suggest you to pass your feedback/feature request in the feedback forum here.
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